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USGS1965

Effects of field applications of heptachlor on bobwhite quail and other wild animals

A study of the effects of field applications of heptachlor on bobwhite quail ( Colinus uirginianus ) and other animals was conducted on three similar areas, two in Decatur County, Georgia, and one in Escambia County, Alabama, from February, 1958, to March, 1962. Heptachlor in granules was applied by aircraft on the Georgia areas for eradication of the imported fire ant ( Solenopsis saevissima ). Applications were directed by personnel of the U. S. Department of Agriculture, Plant Pest Control Division. The Alabama area remained untreated. Transects where whistling cocks were counted were superimposed on areas where coveys were counted. Size of areas varied from 14,000 to 20,000 acres. Each area had six transects, totaling 11,000 acres. Whistling cock bobwhites and coveys averaged 28 and 20 per 1,000 acres, respectively, the year before treatment on a Georgia area, and cocks and coveys averaged 25 per 1,000 acres for the duration of the study on the untreated Alabama area. Where portions of an area were treated at 2 pounds of heptachlor per acre, whistling cocks and coveys were reduced significantly, with a greater reduction where a greater amount of land was treated on the area or its transects. A decline of cocks and coveys also followed 1/2-pound applications (approaching statistical significance for coveys). Three years after treatment, cock and covey numbers were below those recorded before treatment. Whistling cocks and coveys also declined on adjoining land which remained untreated (significant for cocks, approaching significance for coveys). This decline was attributed to movements of bobwhites from untreated land to repopulate treated land. There is evidence that some loss occurred in bobwhites after they moved from untreated to treated land; the decrease in each instance was ascribed to the application of heptachlor. Songbirds were listed on the two Georgia areas. The first summer, eight more species and 458 more individuals of permanent resident birds were listed on the untreated area than on the treated area. After half of the originally untreated area was treated with heptachlor at 2 pounds per acre the following winter, the number of resident birds declined 37 percent. Some species of summer resident birds could not be found on treated land after heptachlor was applied. A small plot of 4 acres was intensively searched for dead and dying animals, and observations were made on living animals. Forty-seven days after treatment, no live animals were seen or heard on the plot, and a total of 38 dead animals had been found. Soils were sampled twice after treatment, and residues had declined in the second lot of samples. Twice animals also were obtained for analysis, and residues declined in the second group. Numbers of birds increased in the same period.

Alabama, Georgia↗

USGS2007

Mercury sedimentation in lakes in western Whatcom County, Washington, USA and its relation to local industrial and municipal atmospheric sources

Concentrations of mercury (Hg) were measured in six dated cores from four lakes in western Whatcom County, Washington, USA, that were at various bearings from a chlor-alkali plant, two municipal waste incinerators and a municipal sewage sludge incinerator. The importance of atmospheric emissions of Hg from these local municipal and industrial sources was evaluating by comparing the temporal trends in sedimentation of the lake cores with the emission history of each Hg species and by examining the geographical distribution of Hg sedimentation in relation to the region's primary wind pattern. Local municipal and industrial sources of atmospheric Hg were not responsible for the majority of the Hg in the upper layer of sediments of Whatcom County lakes because of (1) the significant enrichment of Hg in lake sediments prior to emissions of local industrial and municipal sources in 1964, (2) smaller increases in Hg concentrations occurred after 1964, (3) the similarity of maximum enrichments found in Whatcom County lakes to those in rural lakes around the world, (4) the inconsistency of the temporal trends in Hg sedimentation with the local emission history, and (5) the inconsistency of the geographic trends in Hg sedimentation with estimated deposition. Maximum enrichment ratios of Hg in lake sediments between 2 and 3 that are similar to rural areas in Alaska, Minnesota, and New England suggest that global sources of Hg were primarily responsible for increases of Hg in Whatcom County lakes beginning about 1900. ?? 2007 GovernmentEmployee: U.S. Government, Department of Interior, U.S. Geological Survey.

Water, Air, & Soil Pollution↗

USGS2006

Physical and vegetative characteristics of a relocated stream reach, constructed wetland, and riparian buffer, Upper Saucon Township, Lehigh County, Pennsylvania, 2000-04

The U.S. Geological Survey, in cooperation with the Pennsylvania Department of Transportation, Engineering District 5-0, investigated physical and vegetative changes within a relocated stream reach, constructed wetland, and riparian buffer from September 2000 to October 2004. This report presents an evaluation of data collected using methods from multiple sources that have been adapted into a consistent approach. This approach is intended to satisfy a need for consistent collection of different types of data with the goal of transferring technology and findings to similar projects. Survey data indicate that adjustment of the upstream part of the relocated stream reach slowed over the monitoring period, but the downstream channel remains unstable as evidenced by excessive deposition. Upstream migration of a nick point has slowed or stopped altogether as of the 2003 assessment when this feature came in contact with the upstream-most part of the channel that is lined with riprap. Documented streambed erosion in the upstream cross sections, along with deposition downstream, has resulted in an overall decrease in slope of the stream channel over the monitoring period. Most streambed erosion took place prior to the 2002 assessment when annual mean streamflows were less than those in the final 2 years of monitoring. An abundance of fine sediment dominates the substrate of the relocated channel. Annual fluctuations of large particles within each cross section demonstrates the capacity of the relocated channel to transport the entire range of sediment. The substrate within the 0.28-acre constructed wetland (a mixture of soil from an off-site naturally occurring wetland and woodchips) supported a hydrophytic-vegetation community throughout the investigation. Eleocharis obtusa (spike rush), an obligate-wetland herb, was the most prevalent species, having a maximum areal cover of 90 percent in fall 2001 and a minimum of 23 percent in fall 2004. Drought-like conditions in water year 2002 (cumulative precipitation was 28.11 inches) allowed species like Panicum dichotomiflorum (witch grass), Salix sp. (willow), Leersia oryzoides (rice cutgrass), and Echinocloa crusgalli (barnyard grass) to become established by fall 2002. Above-average precipitation in water years 2003 and 2004 (58.55 and 53.17 inches, respectively) coincided with increased areal cover by E. obtusa in fall 2003 (56 percent) and decreased areal cover in fall 2004 (23 percent). Pond-like conditions that probably persisted throughout the 2004 growing season favored aquatic species like Alisma subcordatum (water plantain) to the detriment of many emergent species, including E. obtusa. Despite the pond-like conditions, L. oryzoides, an obligate-wetland grass, increased in areal cover (from 12 to 34 percent) between the 2003 and 2004 growing seasons because it was established in the higher elevations and the peripheral areas of the constructed wetland that were less prone to persistent inundation. Canopy development by trees and shrubs in the riparian buffer was initially (fall 2000) poor (39.7 percent), resulting in more available sunlight for the herbaceous understory than in any other growing season. As a result, areal cover of herbaceous species and trees and shrubs less than 1-meter tall was 108 percent in fall 2000 with Lolium perenne (perennial rye), Polygonum persicaria (lady's thumb), and Setaria faberi (foxtail) collectively contributing nearly half the cover (59.2 percent). Because of increases in canopy cover by trees and shrubs (39.7 percent in fall 2000 to 127 percent in fall 2004), herbaceous cover decreased to 76 percent by the fall of 2001 and varied between 72 and 77 percent for the rest of the study period. Tree density in the riparian buffer ranged from 3,078 and 4,130 plants per acre (fall 2000 and 2003, respectively) over the study period but essentially remained constant after fall 2001; computations reported each fall between fall 2001 and fall 2004 are within 10 percent of one another. When the study ended in fall 2004, Acer negundo (box elder) and Fraxinus pennsylvanica (green ash) were the most populous tree species (1,526 and 1,084 plants per acre, respectively) followed by Quercus bicolor (swamp white oak; 720 plants per acre). A. negundo , F. pennsylvanica , and Q. bicolor also contributed the greatest areal cover in fall 2004 (31.2, 24.0, and 18.5 percent,respectively).

Pennsylvania↗

USGS2018

Improving understanding of soil organic matter dynamics by triangulating theories, measurements, and models

Soil organic matter (SOM) turnover increasingly is conceptualized as a tension between accessibility to microorganisms and protection from decomposition via physical and chemical association with minerals in emerging soil biogeochemical theory. Yet, these components are missing from the original mathematical models of belowground carbon dynamics and remain underrepresented in more recent compartmental models that separate SOM into discrete pools with differing turnover times. Thus, a gap currently exists between the emergent understanding of SOM dynamics and our ability to improve terrestrial biogeochemical projections that rely on the existing models. In this opinion paper, we portray the SOM paradigm as a triangle composed of three nodes: conceptual theory, analytical measurement, and numerical models. In successful approaches, we contend that the nodes are connected—models capture the essential features of dominant theories while measurement tools generate data adequate to parameterize and evaluate the models—and balanced—models can inspire new theories via emergent behaviors, pushing empiricists to come up with new measurements. Many exciting advances recently pushed the boundaries on one or more nodes. However, newly integrated triangles have yet to coalesce. We conclude that our ability to incorporate mechanisms of microbial decomposition and physicochemical protection into predictions of SOM change is limited by current disconnections and imbalances among theory, measurement, and modeling. Opportunities to reintegrate the three components of the SOM paradigm exist by carefully considering their linkages and feedbacks at specific scales of observation.

Biogeochemistry↗

USGS1996

Analysis of nutrients in the surface waters of the Georgia–Florida Coastal Plain study unit, 1970–91

During the early phase of the Georgia-Florida National Water Quality Assessment study, existing information on nutrients was compiled and analyzed in order to evaluate the nutrient concentrations within the 61,545 square mile study unit. Evaluation of the nutrient concentrations collected at surface-water sites between October 1, 1970, and September 30, 1991, utilized the environmental characteristics of land resource provinces, land use, and nonpoint and point-source discharges within the study unit. Long-term trends were investigated to determine the temporal distribution of nutrient concentrations. In order to determine a level of concern for nutrient concentrations, the U.S. Environmental Protection Agency (USEPA) guidelines were used: (1) for nitrate concentrations, the maximum contaminant level in public-drinking water supplies (10 mg/L); (2) for ammonia concentrations, the chronic exposure of aquatic organisms to un-ionized ammonia (2.1 mg/L); (3) for total-phosphorus concentrations, the recommended concentration in flowing water to discourage excessive growth of aquatic plants (0.1 mg/L); and (4) for kjeldahl concentrations, however, no guidelines were available. For sites within the 10 major river basins, median nutrient concentrations were enerally below USEPA guidelines, except for total-phosphorus concentrations where 45 percent of the medians exceeded the guideline. The only median ammonia concentration that exceeded the guideline occurred at the Swift Creek site (3.4 mg/L), in the Suwannee River basin, perhaps due to wastewater discharges. For all sites within the Withlacoochee, Aucilla, and St. Marys River basins, median concentrations of nitrate, ammonia, and total phosphorus were below the USEPA guidelines. Nutrient data at each monitoring site within each major basin were aggregated for comparisons of median nutrient concentrations among major basins. The Ochlockonee and Hillsborough River basins had the highest median nutrient concentrations, the Aucilla River basin had the lowest. Median concentrations of nitrate and ammonia among all major basins were below USEPA guidelines. The median total-phosphorus concentrations for the following river basins exceeded the USEPA guideline: Hillsborough, St. Johns, Suwannee, Ochlockonee, Satilla, Altamaha, and Ogeechee. Although nutrient concentrations within the study unit were low, long-term increasing trends were found in all four nutrients. All 18 study-unit wide nitrate trends had increasing slopes ranging from less than 0.01 to 0.07 (mg/L)/yr. The range in slope for the 13 ammonia trends was -0.03 to 0.01 (mg/L)/yr with 6 increasing trends in the northern part of the study unit. Of the 17 total-phosphorus trends found in the study unit, 10 were found at sites where the median concentration exceeded the USEPA guideline. At these 10 sites, 4 sites had increasing trends with slopes ranging from less than 0.01 to 0.07 (mg/L)/yr, 5 sites had decreasing trends with slopes ranging from -0.01 to -0.24 (mg/L)/yr, and one site showed a seasonal concentration trend. Median nutrient concentrations were significantly different among the four land resource provinces: Southern Piedmont, Southern Coastal Plain, Coastal Flatwoods, and Central Florida Ridge. As a result, nutrient concentrations among basins with similar nutrient inputs but located within different land resource provinces are not expected to be the same due to differences in the combination of factors such as soil permeability, runoff rates, and stream channel slopes. This concept is an important consideration in designing a surface-water quality network within the study area. For the most part, the Coastal Flatwoods showed the lowest median nutrient concentrations and the Southern Coastal Plain had the highest median nutrient concentrations. Lower median nitrate concentrations in surface-water basins were associated with the forest/wetland land-use category and higher median concentrations of nitrate and ammonia with the urban category when land-use percentages were classified into four land-use categories (agriculture, forest/wetland, mixed, and urban). These results were reasonable based on expected high nutrient inputs from urban areas and low inputs from forested and wetland areas. However, the lack of association between high nutrient concentrations and the agricultural land-use category was not expected since high nutrient inputs are generally needed for agriculture production.

Florida, Georgia↗

USGS2001

Occurrence, distribution, and transport of nutrients in Eastern Iowa Rivers

Eleven streams in the Wapsipinicon, Cedar, Iowa, and Skunk River basins in eastern Iowa were sampled monthly from March 1996 through September 1998 to assess the occurrence, distribution, and transport of nitrogen, phosphorus, and suspended sediment as part of the U.S. Geological Survey's National Water-Quality Assessment Program. At least one form of dissolved nitrogen and phosphorus was detected in every sample collected. Nitrate accounted for 92 percent of the dissolved nitrogen. About 22 percent of the samples contained nitrate that exceeded the U.S. Environmental Protection Agency's Maximum Contaminant Level of 10 milligrams per liter (mg/L) as nitrogen in drinking water. The median concentration of total nitrogen for surface water in the study area was 7.2 mg/L. Dissolved phosphorus was predominately in the form of orthophosphate. The median total phosphorus concentration for the study area was 0.22 mg/L. About 75 percent of the total phosphorus concentrations exceeded the U.S. Environmental Protection Agency recommended total phosphorus concentration of 0.10 mg/L or less to minimize algal growth in streams not discharging directly into lakes or impoundments. Median suspended-sediment concentration for the study area was 82 mg/L. Nitrogen, phosphorus, and suspended-sediment concentrations varied annually and seasonally. Nitrogen, phosphorus, and suspended-sediment concentrations increased each year of the study due to increased precipitation and runoff. Concentrations were typically higher in the spring after fertilizer application and runoff. In winter, nitrogen concentrations typically increased when there was little instream assimilation by aquatic plants and algae. Nitrogen and phosphorus concentrations decreased in late summer when there was less runoff and instream assimilation of nitrogen and phosphorus by aquatic plants and algae was high. Suspended-sediment concentrations were highest in early summer during runoff and lowest in January when there was ice cover with very little overland flow contributing to rivers and streams. Streams draining small- to medium-sized watersheds that have uniform land use and geology had significantly (p < 0.05) higher total dissolved-nitrogen concentrations (median, 8.2 mg/L) than did samples from large rivers (median, 6.2 mg/L) that drain basins with mixed land use and geology. Samples from large rivers typically had significantly (p< 0.05) higher total phosphorus and suspended-sediment concentrations than did samples from small rivers and streams. Concentrations varied between drainage basins due to land use and physiography. Basins that are located in areas with a higher percentage of row-crop agriculture typically had samples with higher nitrogen concentrations than did basins with less row-crop agriculture. In addition, basins that drain the Southern Iowa Drift Plain and the Des Moines Lobe typically had samples with higher total phosphorus and suspended-sediment concentrations than did basins that drain other landform regions. Total nitrogen and total phosphorus loads were typically proportional to the size of the drainage basin. Total nitrogen loads increased each year from 1996 through 1998 in conjunction with increased concentrations and runoff. However, total phosphorus loads in the Skunk River Basin decreased in 1997 due to less runoff. Total phosphorus loads followed the same pattern as total nitrogen loads with increases in 1998. Total nitrogen and total phosphorus loads varied seasonally and the highest loads typically occurred in early spring and summer after fertilizer application and runoff. Loads were lowest in January and September when there was little runoff to transport nitrogen and phosphorus to the rivers and streams. Total nitrogen loads contributed to the Mississippi River from the Eastern Iowa Basins during 1996, 1997, and 1998 were 97,000, 120,000, and 230,000 metric tons respectively. Total phosphorus loads contributed to the Mississippi River from the Eastern Iowa Basins during 1996, 1997, and 1998 were 6,900, 4,600, and 8,800 metric tons, respectively. The highest nitrogen and phosphorus yields typically occurred in streams draining small watersheds that were dominated by a single land use and geology. Sampling sites located in drainage basins with higher row-crop percentage typically had higher nitrogen and phosphorus yields. Sites that were located in the Des Moines Lobe and the Southern Iowa Drift Plain typically had higher phosphorus yields probably due to more erodible soils and steeper slopes.

Iowa↗

USGS2020

The field trip that changed the course of my career

After gobbling down a breakfast of sliced papaya, scrambled eggs, refried beans, and soft flour tacos, we gathered our gear and loaded it into the red zodiac that the station manager had assigned to us. My colleagues and I were headed to a pair of islands off the coast of Belize called Twin Cays, occupied by a unique group of tropical plants and animals adapted to a wet and saline habitat. Our ride from Carrie Bow Cay, home of the Smithsonian Institution’s field station, took about twenty minutes because of the choppy water. As we crossed the three-kilometer stretch from Carrie Bow to Twin Cays, I struggled to keep my seat on the bouncing pontoon and was soon soaked by salt spray. As we neared Twin Cays, the deep blue of the lagoon gave way to the turquoise and pale green colors of the shallow sand flats in the lee of the archipelago. Finally, the zodiac slowed, and we pulled into the calm channel separating the two islands. On either side of the channel was an intimidating tangle of tree trunks, branches, leaves, and aerial roots. The trees leaned out over the water and appeared poised to topple into the sea. However, they were perfectly still in the humid morning air and anchored solidly in place by arching prop roots. I sensed that I had entered an alien world, a waterlogged Terra Incognita that looked, smelled, and sounded like nothing I had ever experienced. As we slowly motored along, I peered more closely at the trees that fringed the shoreline. They had gnarled trunks and twisted branches that supported a canopy of dark green leaves. These trees were red mangroves or Rhizophora mangle, their scientific name, and were the dominant vegetation here. These oceanic mangrove islands were intertidal, which means that the trees were inundated twice a day by the sea. Their intimate relationship with the sea, however, was most apparent along the water’s edge. Long, drop roots plunged from the canopy to dangle in the crystal-clear water. Encrusted on the submerged portions of the mangrove roots were yellow and orange sponges, white and pink anemones, sharp-edged oysters, and feathery-green algae. The mangroves, it turned out, provided the only solid substrate for these sessile creatures. There were also mobile animals that I glimpsed as I leaned over the pontoon to peer into the pellucid water. Tiny fish flashed among the partially submerged roots as each one briefly flipped its body sideways to catch the sun glinting through the water. A school of mangrove snappers swam past the boat and disappeared under the overhanging creekbank, which created a shadowy haven from predators. Ribbons of turtlegrass, uprooted from the nearby reef flat, were draped on mangrove prop roots like green and brown tinsel. As the zodiac floated closer to shore, I spotted a mangrove tree crab, which stealthily crept up a tree trunk. In the distance, I could hear the hectoring cry of an osprey, as well as the periodic cheep-cheep of a mangrove warbler deeper in the forest. A soft breeze carried the faint odor of rotten eggs, which was caused by the microbially mediated production of hydrogen sulfide in the waterlogged soil. This was my first close-up view of Belize’s mangroves. The year was 1985. The movie “Back to the Future” had just premiered, PLO terrorists had hijacked the Italian cruise ship Achille Lauro, five people had died after ingesting cyanide-laced Tylenol, and Microsoft had just released Windows 1.0. I had recently gotten a Macintosh personal computer with 128k of memory (seemed like a lot back then) and was learning how to use Cricket Graph, my first software program. Until that point, I had been creating graphs by hand with ink-filled drawing pens, T-squares, and Letraset dry-transfer sheets. This was a time when the world seemed to be on the verge of dramatic changes—many that would impact me and my career as a scientist.

Book chapter↗

USGS2013

The distribution of uranium over Europe: Geological and environmental significance

The variation of baseline levels of uranium in soil and stream sediments over Europe is described, based on new data prepared by the Forum of European Geological Surveys (FOREGS). The samples have been collected and analysed according to the protocols established for the International Union of Geological Sciences/International Association of Geochemistry and Cosmochemistry (IUGS/IAGC) Working Group on Global Geochemical Baselines. The baseline levels of U vary between 0??21 to 53 mg kg-1 in topsoils, 0??19 to 30 mg kg-1 in subsoils and < 1 to 59 mg kg-1 in stream sediments. There is generally good agreement between the levels of U in the three sample types, and the median concentration in all three media is approximately 2 mg kg-1. The most anomalous baseline levels occur over the Variscan orogen, especially areas into which late post-orogenic radiothermal high heat production (HHP) granites were emplaced. Spiderdiagrams based on trace element levels and rare earth element (REE) plots, confirm the association between the highest U anomalies and evolved radiothermal granites. High values are also associated with parts of the Alpine terrain especially in Slovenia, where there are historical U workings, and Southern Italy, where high values of U reflect contemporary volcanism. In contrast, much of the Caledonides of North West Europe and the Precambrian of the Baltic Shield and East European craton and its overlying sedimentary cover have very low values, generally < 4 mg kg-1. The results suggest that the main concern for the environment and human health from U, and the Th and K with which it is generally associated, is the naturally occurring total gamma radiation and radon potential associated with radiothermal granites. This is likely to be especially important where the granites are mineralised and have been worked historically, for example in the North West of the Iberian Peninsula where U and its decay products are likely to be more dispersed in the surface environment. The study also indicates the value of multi-element data in distinguishing between anthropogenic and naturally occurring anomalies.

Transactions of the Institution of Mining and Meta↗

USGS2024

Distribution, abundance, and breeding activities of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2020 annual report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton (MCBCP, or Base). Surveys for the Least Bell's Vireo were conducted at MCBCP, California, between April 1 and July 10, 2020. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed 3–4 times. We detected 669 territorial male vireos and 16 transient vireos in core survey areas. An additional 156 territorial male vireos were detected in non-core survey areas. Territorial vireos were detected on all 10 drainages/sites surveyed (core and non-core areas). Of the vireo territories in core areas, 88 percent were on the 4 most populated drainages, with the Santa Margarita River containing 69 percent of all territories. In core areas, 79 percent of male vireos were confirmed as paired; 83 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP (669) increased 39 percent from 2019 to 2020. The number of territories in all core survey area drainages increased by one or more between 2019 and 2020. The substantial increase in vireo numbers on MCBCP (39 percent) was consistent with population changes in surrounding areas, including the lower San Luis Rey River (26 percent), Marine Corps Air Station, Camp Pendleton (58 percent), and the middle San Luis Rey River (7 percent). Most core-area vireo territories (69 percent of males) occurred in willow ( Salix spp.) riparian habitat. An additional 4 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ) or Fremont cottonwoods ( Populus fremontii ). Eighteen percent of territories were found in riparian scrub dominated by mule fat ( Baccharis salicifolia ) or sandbar willow ( S. exigua ). Upland scrub was used by 7 percent or fewer vireos; 1 percent of territories occurred in non-native vegetation, and less than 1 percent of vireo territories occurred in habitat co-dominated by coast live oak ( Quercus agrifolia ) and sycamore. In 2019, MCBCP began operating an artificial seep along the Santa Margarita River. The artificial seep pumped water to the surface from March through August each year during daylight hours and was designed to increase the amount of surface water present to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ; flycatcher) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited the seep and proposed seep areas within the past several years. Therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents preliminary analyses of vireo and vegetation response to the existing artificial seep. We sampled vegetation in the Seep site and three Reference sites to determine the effects of a new water diversion dam that was completed in 2019 and a surface water enhancement seep pump installed along the Santa Margarita River. We found minor differences in non-native vegetation cover between Reference sites and the Seep site. However, soil moisture was higher at the Reference sites compared to the Seep site. The effect of the seep pump may have been masked by high precipitation in the bio-year (July 1‒June 30) before 2020, limited time for the water diversion to have an effect, well-draining soil, and the non-operation of two to three of the six seep outlets. We color banded and resighted color banded Least Bell’s Vireos to evaluate adult site fidelity, between-year movement, and the effect of surface water enhancement on vireo site fidelity and between-year movement. We banded 146 Least Bell's Vireos for the first time during the 2020 season. Birds banded included 27 adult vireos and 119 juvenile vireos. All adult vireos were banded with unique color combinations. The juvenile vireos (all nestlings) were banded with a single gold numbered federal band on the left leg. We resighted and identified 85 Least Bell's Vireos banded before the 2020 breeding season on Base in 2020. Of the 85, 13 vireos were originally banded on the San Luis Rey River, 2 were banded in Baja California Sur, 1 was banded at Marine Corps Air Station, Camp Pendleton, and the remaining birds were banded at MCBCP. Adult birds of known age ranged from 1 to 8 years old. Most returning adult vireos showed strong between-year site fidelity. Of the adults present in 2019 and 2020, 74 percent, (79 percent of males; 40 percent of females) returned to within 100 m of their previous territory. The average between-year movement for returning adult vireos was 0.3 plus or minus (±) 0.8 kilometer (km). The average movement of first-year vireos detected in 2020 that fledged from a known nest on MCBCP in 2019 was 4.7±7.0 km. One first-year vireo that originated at MCBCP moved off Base and was detected at Murrieta Creek, 23.0 km from his natal territory. We monitored Least Bell's Vireo pairs to evaluate the effects of surface water enhancement on nest success and breeding productivity. Vireos were monitored at one Seep site and three Reference sites. Base personnel plan to install a second seep pump at one of the Reference sites in the future, at which time the status of the monitoring site will change from Reference to Seep. Nesting activity was monitored between March 31 and July 28 in 52 territories within the Seep and Reference sites (12 at the Seep site and 40 at Reference sites). All territories were occupied by pairs, and all but one territory was fully monitored, meaning all nesting attempts were monitored at these territories. One vireo territory within a Reference site was partially monitored. During the monitoring period, 94 nests (25 in the Seep site and 69 in Reference sites) were monitored. Breeding productivity was similar at the Seep site and Reference sites (3.7 and 2.9 young per pair, respectively), with 75 percent of Seep pairs and 79 percent of Reference pairs successfully fledging at least 1 young in 2020. Compared to Reference sites, the Seep site had a higher proportion of all eggs that hatched and also a higher proportion of nests with eggs that hatched. Conversely, a lower proportion of hatchlings and nests that had hatchlings fledged at the Seep site than at Reference sites. According to the best model, nest survival in 2020 was not affected by treatment (Seep versus Reference), although the second best model that included treatment was also well supported. Completed nests at the Seep site were likely to be as successful as nests at Reference sites in 2020 (57 percent and 59 percent, respectively). Predation was believed to be the primary source of nest failure at both sites. Predation accounted for 90 percent and 73 percent of nest failures at Seep and Reference sites, respectively. Failure of the remaining eight nests was attributed to the collapse of the nesting substrate, exposure to rain and flooding, and other unknown reasons. Fourteen plant species were used as hosts for vireo nests in 2020. In 2020, we found that at the Seep site, successful nests were placed in taller host plants and further from the edge of host plants (closer to the center) than unsuccessful nests. We found no difference in nest placement between the Seep site and the Reference sites.

California↗

USGS2024

Distribution, abundance, and breeding activities of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2021 annual report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton (MCBCP or “Base”). Surveys for the Least Bell's Vireo were completed at MCBCP, California, between April 5 and July 13, 2021. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed three to four times. We detected 551 territorial male vireos and 26 transient vireos in core survey areas. An additional 98 territorial male vireos were detected in non-core survey areas. Transient vireos were detected on 8 of the 10 drainages/sites surveyed (core and non-core areas). Of the vireo territories in core areas, 89 percent were on the four most populated drainages, with the Santa Margarita River containing 70 percent of all territories in areas surveyed on Base. In core areas, 75 percent of male vireos were confirmed as paired; 76 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP decreased 18 percent from 2020 to 2021. The number of territories in all but two core survey area drainages decreased by one or more between 2020 and 2021. The decrease in vireo numbers on MCBCP (18 percent) was consistent with population changes in surrounding areas, including the lower San Luis Rey River (24-percent decrease) and the middle San Luis Rey River (6-percent decrease). Most core-area vireo territories (59 percent of males) were in willow ( Salix spp.) riparian habitat. An additional 7 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ) or Fremont cottonwoods ( Populus fremontii ). Of all the territories surveyed, 25 percent were in riparian scrub dominated by mule fat ( Baccharis salicifolia ) or sandbar willow ( S. exigua ). Upland scrub was used by 8 percent of vireos; 1 percent of vireo territories were in non-native vegetation, and less than 1 percent of vireo territories were in alder or drier habitats co-dominated by coast live oak ( Quercus agrifolia ) and sycamore. In 2019, MCBCP began operating an artificial seep along the Santa Margarita River; then, in 2021, two additional artificial seeps became operational. The artificial seeps pumped water to the surface starting in March and ending in August each year during daylight hours and were designed to increase the amount of surface water present to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited the seep areas within the past several years; therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents the second year of analyses of vireo and vegetation response to the artificial seeps. We sampled vegetation in two Seep sites and two Reference sites to determine the effects of a new water diversion dam that was completed in 2019 and two seep pumps that were installed to enhance surface water along the Santa Margarita River in 2019 and 2021. We measured higher total vegetation cover below 2 meters (m) at Seep sites than at Reference sites and lower total vegetation cover above 5 m at Seep sites than at Reference sites. Native herbaceous cover was also higher below 4 m at Seep sites than at Reference sites. Woody cover was lower above 5 m at Seep sites than at Reference sites. Soil moisture did not differ between Seep and Reference sites. The U.S. Geological Survey has been color banding Least Bell’s Vireos on Marine Corps Base Camp Pendleton since 1995. In 2021, we continued to color band and resight color banded Least Bell’s Vireos to evaluate adult site fidelity, between-year movement, and the effect of surface-water enhancement on vireo site fidelity and between-year movement. We banded 164 Least Bell's Vireos for the first time during the 2021 season. Birds banded included 3 adult vireos and 161 juvenile vireos. All adult vireos were banded with unique color combinations. The juvenile vireos (all nestlings) were banded with a single gold numbered federal band on the right leg. There were 52 Least Bell's Vireos banded before the 2021 breeding season that were resighted and identified on Base in 2021. Of these vireos, 45 were banded on Base, 6 were originally banded on the San Luis Rey River, and 1 was banded at Marine Corps Air Station, Camp Pendleton. Adult birds of known age ranged from 1 to at least 7 years old. Base-wide survival of vireos was affected by sex, age, and year. Males had a slightly but significantly higher survival rate than females. Adults had a higher survival rate than first-year vireos. Survival of both adults and first-year birds was high from 2007 to 2008 and from 2012 to 2013 and low from 2020 to 2021. The return rate of adult vireos to Seep or Reference sites ranged from 45 to 57 percent. Most returning adult vireos showed strong between-year site fidelity. Of the adults present in 2020 and 2021, 84 percent (94 percent of males; no females) returned to within 100 m of their previous territory. The average between-year movement for returning adult vireos was 0.1±0.2 kilometer (km). The average movement of first-year vireos detected in 2021 that fledged from a known nest on MCBCP in 2020 was 1.1±0.7 km. We monitored Least Bell's Vireo pairs to evaluate the effects of surface-water enhancement on nest success and breeding productivity. Vireos were monitored at two Seep sites and two Reference sites. Early in 2021, a seep was installed in a 2020 Reference site, which changed the status of this monitoring site from Reference to Seep. Nesting activity was monitored between April 5 and July 22 in 50 territories within the Seep and Reference sites (25 at Seep sites and 25 at Reference sites). All territories, except one, were occupied by pairs and all were fully monitored, meaning all nesting attempts were monitored at these territories. During the monitoring period, 97 nests (42 in Seep sites and 55 in Reference sites) were monitored. Breeding productivity was similar at the Seep site and Reference sites (3.6 and 3.4 young per pair, respectively), with 84 percent of Seep pairs and 88 percent of Reference pairs successfully fledging at least one young in 2021. Seep sites had a higher proportion of all eggs that hatched and also a higher proportion of nests with eggs that hatched than Reference sites. Seep sites and References sites had similar proportions of hatchlings that fledged and nests with hatchlings that fledged. According to the best model, daily nest survival in 2021 was higher in Seep sites than in Reference sites. Completed nests at the Seep site were more likely to be successful than nests at Reference sites in 2021. At Seep sites, 75 percent of nests fledged young, whereas 53 percent of nests at Reference successfully fledged young. Vireos at Reference sites had to expend more energy in extra nest-building and egg-laying to produce a similar number of young as vireos at Seep sites. Predation was believed to be the primary source of nest failure at both sites. Predation accounted for 100 percent and 83 percent of nest failures at Seep and Reference sites, respectively. Failure of the remaining nests was attributed to infertile eggs and other unknown causes. There were 11 plant species used as hosts for vireo nests in 2021. Successful vireo nests at Reference sites were further from the edge of host plants (closer to the center) and further from the edge of the nest plant clump than unsuccessful nests. Vireo nests at Seep sites were further from the edge of the host plant and the nest plant clump than vireo nests at Reference sites.

California↗

USGS2000

Sources, instream transport, and trends of nitrogen, phosphorus, and sediment in the lower Tennessee River basin, 1980-96

In 1997, the U.S. Geological Survey (USGS) began an assessment of the lower Tennessee River Basin as part of the National Water-Quality Assessment Program. Existing nutrient and sediment data from 1980 to 1996 were compiled, screened, and interpreted to estimate watershed inputs from nutrient sources, provide a general description of the distribution and transport of nutrients and sediments in surface water, and evaluate trends in nutrient and sediment concentrations in the lower Tennessee (LTEN) River Basin. Nitrogen inputs from major sources varied widely among tributary basins in the LTEN River Basin. Point source wastewater discharges contributed between 0 and 0.61 tons per square mile per year [(tons/mi 2 )/yr]. Of the nonpoint sources of nitrogen for which inputs were estimated (atmospheric deposition, nitrogen fixation, fertilizer application, and livestock waste) livestock waste contributed the largest input in about two-thirds (7 out of 11) of the tributary basins, and fertilizer application contributed the largest input in the remaining 4 basins. Nitrogen input from fertilizer application was the most variable spatially among the nonpoint sources of nitrogen, ranging from 1.5 to 23 (tons/mi 2 )/yr. Atmospheric deposition estimates varied the least from basin to basin, ranging from 1.6 to 2.0 (tons/mi 2 )/yr. Estimates of nitrogen input from livestock waste ranged between 2.0 to 13 (tons/mi 2 )/yr. The percentage of the input from each of these nonpoint sources that entered the surface-water system is not known. Wastewater discharge contributed between 0 and 0.14 (ton/mi 2 )/yr of phosphorus to tributary basins. Livestock waste contributed most of the input in 8 out of the 11 basins, and fertilizer application contributed the most in the remaining 3 basins. Estimates of phosphorus input for fertilizer application ranged from 0.35 to 5.1 (tons/mi 2 )/yr and from 0.62 to 4.3 (tons/mi 2 )/yr from livestock waste. Reservoirs on the main stem of the Tennessee River and on the Duck and Elk Rivers affect nutrient transport because hydrodynamic conditions in the reservoirs promote assimilation by aquatic plants and deposition of particulate matter. Observed decreases in total nitrite plus nitrate and dissolved-orthophosphorus concentrations in reservoirs or at sites downstream of reservoirs during summer months were probably related to seasonality of plant growth. Nutrient and sediment data used to estimate annual instream loads and yields were compiled from various water-quality monitoring programs and represent the best available data in the LTEN River Basin, but these data have several characteristics that limit accuracy of load estimates. Many of the monitoring programs were not designed with the objective of annual load estimation, and data representing storm transport are, therefore, sparse; sampling and analytical methods varied through time and among the monitoring programs, hampering spatial and temporal comparisons. The load estimates computed from these data are useful for evaluating broad spatial patterns of instream load, and comparisons of instream load to inputs, but may not be sufficiently accurate for local-scale evaluations of water quality. Estimates of the mean annual instream load of total nitrogen entering (Chattanooga, Tenn.) and leaving (Paducah, Ky.) the LTEN River Basin were 29,000 and 60,000 tons per year (tons/yr), respectively. These estimates represent a gain of 31,000 tons/yr, on average, across the area (18,930 mi 2 ) between these inlet and outlet sites. The sum of the mean annual instream load from gaged tributaries to the main stem within the study unit was 14,000 tons/yr; however, this number cannot be directly compared with the gain between the inlet and outlet sites because (1) the gaged area represents only 30 percent of the total area and (2) the period of record at many tributary sites did not correspond with the period of record at the inlet or outlet sites. Estimates of mean annual instream load of total phosphorus at the inlet and outlet sites of the LTEN River Basin were 1,300 and 5,000 tons/yr, respectively, representing a gain of 3,700 tons/yr, on average, across the study unit. The sum of the gaged tributary load, representing only 28 percent of the area contributing to the main stem, was 4,300 tons/yr. Although this number cannot be closely compared with the gain throughout the study unit, for the same reasons given for total nitrogen, a general comparison suggests that the main stem of the Tennessee River and the tributary embayments along the main stem function as a sink for total phosphorus, removing a substantial amount from the water column through deposition or assimilation. The estimates of inputs can be compared and correlated with yields (area-normalized instream loads); significant correlations between estimates of inputs and yields might be useful as predictive tools for instream water quality where monitoring data are not available. Yields of nitrogen correlated moderately well with inputs from nonpoint sources, based on 1992 estimates. Nitrogen yield was highest [3.5 (tons/mi 2 )/yr] for Town Creek, for which the balance of nonpoint-source inputs to agricultural lands (fertilizer application plus nitrogen fixation plus livestock waste minus harvest) was also the highest [15 (tons/mi 2 )/yr]. Nitrogen yield was low [1.0 (tons/mi 2 )/yr] for the Buffalo River, for which the balance of agricultural nonpoint-source input was correspondingly low [3.2 (tons/mi 2 )/yr, the second lowest]. Correlation of wastewater discharge with yield was poor, and contrasted with the significant correlation between wastewater discharge and median nitrogen concentration during low streamflow. The poor correlation between wastewater discharge and annual yield was expected, however, as wastewater discharge is a small fraction compared with annual yield. In contrast with nitrogen, phosphorus yield did not correlate well with any estimated inputs or land-use types for the tributary basins. Phosphorus yield was highest [1.1 and 0.93 (tons/mi 2 )/yr] at two sites along the Duck River and at Elk River near Prospect [0.89 (ton/mi 2 )/yr]; however, estimates of inputs at these sites were in the middle of their respective ranges. The influence of the outcrop of phosphatic limestone formations of the brown-phosphate districts in the lower Duck and lower Elk River Basins might be responsible for the poor correlation between estimated inputs and yields of phosphorus. The outcrop pattern of these phosphatic limestones are an important factor to consider as regional boundaries are established for attainable, region-specific water-quality criteria for total phosphorus. Estimates of sediment input from cropland soil erosion in 1992 ranged from 51 to 540 (tons/mi 2 )/yr among the major hydrologic units in the LTEN River Basin. Information was not available to estimate this input for individual tributaries. Sediment yield estimates ranged from 65 to 263 (tons/mi 2 )/yr for the three tributary monitoring basins for which instream data were available, and from 17 to 26 (tons/mi 2 )/yr for the Tennessee River at South Pittsburg and at Pickwick Landing Dam, respectively. Lower sediment yields for the main stem sites compared with the tributary sites is probably due to sediment deposition in the main stem of the Tennessee River and tributary embayments along the main stem. Most of the significant trends in nutrient concentrations from about 1985 to about 1995 were decreasing trends, except for total nitrite plus nitrate, which increased at one site on the Elk River. The spatial distribution of decreasing trends of total nitrogen and total ammonia corresponds with the spatial variation among basins in wastewater loading rate. The time period of observed trends corresponds to the period of improvements in municipal treatment, thus decreases in wastewater effluent concentrations of nitrogen might be responsible for the decreasing trend in instream concentrations at these sites. Concentrations of total phosphorus did not decrease during this period at these sites, as might have been expected considering the reductions in wastewater input of phosphorus during this period.

Alabama, Georgia, Kentucky, Mississippi, Tennessee↗

USGS2017

Geology and mining history of the Southeast Missouri Barite District and the Valles Mines, Washington, Jefferson, and St. Francois Counties, Missouri

The Southeast Missouri Barite District and the Valles Mines are located in Washington, Jefferson, and St. Francois Counties, Missouri, where barite and lead ore are present together in surficial and near-surface deposits. Lead mining in the area began in the early 1700’s and extended into the early 1900’s. Hand mining of lead in the residuum resulted in widespread pits (also called shafts or diggings), and there was some underground mining of lead in bedrock. By the 1860’s barite was recovered from the residuum by hand mining, also resulting in widespread diggings, but generally not underground mines in bedrock. Mechanized open-pit mining of the residuum for barite began in the 1920’s. Barite production slowed by the 1980’s, and there has not been any barite mining since 1998. Mechanized barite mining resulted in large mined areas and tailings ponds containing waste from barite mills. The U.S. Environmental Protection Agency (EPA) has determined that lead is present in surface soils in Washington and Jefferson Counties at concentrations exceeding health-based screening levels. Also, elevated concentrations of barium, arsenic, and cadmium have been identified in surface soils, and lead concentrations exceeding the Federal drinking-water standard of 15 micrograms per liter have been identified in private drinking-water wells. Potential sources of these contaminants are wastes associated with barite mining, wastes associated with lead mining, or unmined natural deposits of barium, lead, and other metals. As a first step in helping EPA determine the source of soil and groundwater contamination, the U.S. Geological Survey (USGS), in cooperation with the EPA, investigated the geology and mining history of the Southeast Missouri Barite District and the Valles Mines. Ore minerals are barite (barium sulfate), galena (lead sulfide), cerussite (lead carbonate), anglesite (lead sulfate), sphalerite (zinc sulfide), smithsonite (zinc carbonate), and chalcopyrite (copper-iron sulfide). The Cambrian Potosi Dolomite is the most important formation for the ore deposits, followed by the Eminence Dolomite. Because galena, sphalerite, and barite are less soluble than dolomite, chemical weathering of the ore-bearing dolomite bedrock resulted in the concentration of ore minerals in the residuum. Most of the barite and lead mining was in the residuum, which averages 10 to 15 feet thick. Lead mining by French explorers may have begun in 1719 along Old Mines Creek at Cabanage de Renaudiere, which was followed shortly by the discovery of lead and the development of lead mines at Mine Renault (also called Forche a Renault Mine), Old Mines, and at other places along the Big River, Mineral Fork, and Forche a Renault Creek. Lead mining began sometime between 1775 and 1780 at Mine a Breton, the name of which was later changed to Potosi. Other mining areas were developed in the early part of the 19th century, including Fourche a Courtois (Palmer Mines), the French Diggings, and the Richwoods Mines. Zinc became a valuable resource after the Civil War, and the Valles Mines was an important supplier of zinc as well as lead, with at least some production up until the 1920’s. Lead mining declined in the early part of the 20th century as mining in the Old Lead Belt, Mine La Motte, and the Tri-State District expanded. The earliest lead mines were diggings in the residuum and were round holes (shafts) about 4 feet in diameter dug with pick and shovel about 15–20 feet deep, with drifts dug a short distance laterally from the bottom of the shafts. This mining process was repeated a short distance away until a large area was covered with pits. Some mining in bedrock began by about 1800, with shafts as deep as 170 feet and as much as several hundred feet of lateral drifts. Smelting of the lead ore to elemental lead was first done using a log furnace, which was inefficient; estimates have been made that only about 50 percent of the lead was recovered, and the remainder was lost to the ashes (slags) and to volatilization. Starting in 1798, ash furnaces were used to smelt the ashes from the log furnaces. These two furnaces were worked in tandem for many years but were gradually replaced by other furnaces, including the Scotch hearth. Estimates of lead recovery as high as 80–90 percent have been made for the Scotch hearth. By the mid-1870’s the air furnace was being used, also with estimated lead recovery as high as 80–90 percent. Zinc furnaces were built when zinc became a valuable commodity, but much of the zinc ore was shipped out of the area, either to a smelter in St. Louis, Missouri, or to other smelters. The total lead and zinc production from the Southeast Missouri Barite District and the Valles Mines is estimated at 180,000 tons of lead and 60,000 tons of zinc. An estimated 97,000 tons of lead and an estimated 120,000 tons of zinc were lost during smelting. The estimated losses do not include losses at the mine site during mining and preparation for smelting, such as the loss of fine-grained galena during hand cleaning or the discarding of zinc ore before its value was known, for which no estimates are available. Hand mining for barite in the residuum was active by at least the 1860’s and peaked from 1905 to the 1930’s when several thousand people were engaged in barite mining. Hand mining (diggings) and cleaning of the ore was done in much the same way as earlier lead mining, with the additional use of a rattle box to further clean the barite. Mechanized open-pit mining of old barite diggings began in 1924 to recover barite left behind by hand mining, and washing plants were used to clean the clay from the barite. Hand mining, however, continued to thrive, and washer plants began to close temporarily in 1931; nearly all of the barite produced before 1937 was by hand mining. By the 1940’s, however, all barite mining was mechanized. Mechanized mining used shovels powered by steam, gasoline, or electricity (and by the 1950’s draglines and front-end loaders) to mine the residuum. The ore was loaded onto rail cars (and by the 1940’s, trucks) for shipment to washer plants. Clay was removed from the barite using a log washer, and a jig was used to concentrate the barite. Overflow from the log washers was waste and went to a mud (tailings) pond. The coarse jig tailings went to tailings piles or were used as railroad ballast and, later, to create roads within the mine pit. Some barite was ground, depending on its final use, and some ground barite was bleached using a hot solution of sulfuric acid to remove impurities such as iron minerals and lead sulfide (galena). An earlier bleaching process used lead-lined tanks. Large quantities of water were required for milling the barite; some was recirculated water and the remainder came from dammed streams or was pumped from wells. Tailings and wastewater were impounded behind dikes that were built across small valleys and were increased in height as necessary using washer waste and any overburden that had been stripped. In some cases, dikes were built across valleys that had already been mined for barite. The total production of barite from the Southeast Missouri Barite District and the Valles Mines is estimated to have been about 13.1 million tons. Most of the barite production was from Washington County. Hand mining and processing of barite was inefficient. Estimates of barite recovery range from less than one-fourth to about one-half because pillars between the shafts in the residuum needed to be left unmined for stability. With mechanized mining, large amounts of barite were lost during the milling process. It has been estimated that about 30 percent of the barite was lost and that about two-thirds of the lost barite was fine-grained and was discharged to the tailings ponds. Some galena was lost to the tailings ponds. A 1972 inventory of tailings ponds by the Missouri Geological Survey identified 67 ponds in the Southeast Missouri Barite District (there are more than this currently documented). Results from samples from four ponds that were drilled were used to estimate that the 67 ponds contained almost 39 million tons (or cubic yards) of tailings averaging about 5 percent barite, for a potential reserve of 1.935 million tons of barite. It is not known how much lead was removed during barite mining, either by hand or mechanized mining and processing, how much lead was recovered, or how much lead went as fines to the tailing ponds or as coarse material to mine roads or was otherwise lost.

Missouri↗

USGS2024

Distribution, abundance, and breeding activities of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2022 annual report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton (MCBCP or “Base”). Surveys for the Least Bell's Vireo were completed at MCBCP, California, between April 4 and July 12, 2022. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed two to four times. We detected 571 territorial male vireos and 14 transient vireos in core survey areas. An additional 90 territorial male vireos and 2 transients were detected in non-core survey areas. Transient vireos were detected on 7 of the 11 drainages/sites surveyed (core and non-core areas). Of the vireo territories in core areas, 90 percent were on the four most populated drainages, with the Santa Margarita River containing 73 percent of all territories in areas surveyed on Base. In core areas, 81 percent of male vireos were confirmed as paired; 61 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP increased 4 percent from 2021 to 2022. In three core survey area drainages, the number of territories increased by at least two, and in five core survey area drainages, the number of vireo territories decreased by at least two between 2021 and 2022. The increase in the number of vireo territories on MCBCP was consistent with population changes at the lower San Luis Rey River (7-percent increase), but not with Marine Corps Air Station, Camp Pendleton (10-percent decrease). A wildfire in July 2021 burned approximately 22 hectares of vireo habitat on the Santa Margarita River. There was no difference in the number of vireo territories within the fire perimeter before the fire (three territories in 2021) and after the fire (three territories in 2022). Most core-area vireos (52 percent, including transients) used mixed willow (Salix spp.) riparian habitat. An additional 8 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ) or Fremont cottonwoods ( Populus fremontii ). Riparian scrub composed of mule fat ( Baccharis salicifolia ), sandbar willow ( S. exigua ), or blue elderberry ( Sambucus mexicana ) was used at 37 percent of vireo territories. Upland scrub was used by 2 percent of the vireos, and 1 percent of vireo territories were in drier habitats co-dominated by coast live oak (Quercus agrifolia) and sycamore. In 2019, MCBCP began operating an artificial seep along the Santa Margarita River; then, in 2021, two additional artificial seeps became operational. The artificial seeps pumped water to the surface starting in March and ending in August each year during daylight hours and were designed to increase the amount of surface water to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited the seep areas within the past several years; therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents the third year of analyses of vireo and vegetation response to the artificial seeps. We sampled vegetation in two Seep sites and two Reference sites to determine the effects of surface water enhancement by seep pumps installed along the Santa Margarita River. Total vegetation cover below 2 meters (m) was greater at Seep sites than at Reference sites. Conversely, there was more non-native vegetation cover above 2 m (from 2 to 4 m) at Reference sites than at Seep sites. Soil moisture was greater at Seep sites than at Reference sites and decreased with increasing distance from the seep outlets. Soil moisture was positively correlated with total foliage cover and woody cover at most height categories. Soil moisture was not correlated with total herbaceous cover at any height category, although it was positively correlated with native herbaceous cover from 1 to 2 m and negatively correlated with non-native cover from 2 to 4 m. The number of vireo fledglings produced per egg was positively correlated with woody cover from 0 to 2 m but negatively correlated with herbaceous cover from 0 to 2 m. The number of fledglings produced per pair was negatively correlated with herbaceous and non-native vegetation cover below 2 m. The U.S. Geological Survey has been color banding Least Bell’s Vireos on Marine Corps Base Camp Pendleton since 1995. By the end of 2021, 978 Least Bell’s Vireos had been color banded on Base. In 2022, we continued to color band and resight color banded Least Bell’s Vireos to evaluate adult site fidelity, between-year movement, and the effect of surface-water enhancement on vireo site fidelity and between-year movement. We banded 135 Least Bell's Vireos for the first time during the 2022 season. Birds banded included 4 adult vireos and 131 juveniles. All adult vireos were banded with unique color combinations. The juvenile vireos (all nestlings) were banded with a single gold numbered federal band on the left leg. There were 43 Least Bell's Vireos banded before the 2022 breeding season that were resighted and identified on Base in 2022. Of these vireos, 39 were banded on Base, 3 were originally banded on the San Luis Rey River, and 1 was banded at Marine Corps Air Station, Camp Pendleton. Adult birds of known age ranged from 1 to at least 7 years old. Base-wide survival of vireos was affected by sex, age, and year. Males had a significantly higher survival rate than females. Adults had a higher survival rate than first-year vireos. Survival for adults and first-year birds was lowest from 2020 to 2021 and highest from 2012 to 2013. The return rate of adult vireos to Seep or Reference sites was not affected by whether they were originally banded at a Seep versus Reference site. Most of the returning adult vireos showed strong between-year site fidelity. Of the adults detected in 2021 and 2022, 89 percent (92 percent of males; 67 percent of females) returned to within 100 m of their previous territory. The average between-year movement for returning adult vireos was 0.1±0.2 kilometers (km). The average movement of first-year vireos detected in 2022 that fledged from a known nest on MCBCP in 2021 was 1.6±1.8 km. Vireo territory density at the Seep and Reference sites was similar before the seep pumps were installed. Although vireo territory density at Seep sites appeared greater than at Reference sites after the seep pumps were installed, the difference was not significant. We monitored Least Bell’s Vireo pairs to evaluate the effects of surface-water enhancement on nest success and breeding productivity. We monitored vireo nesting activity at 25 territories in 2 Seep sites and 25 territories in 2 Reference sites between March 31 and July 28. All territories except one were occupied by pairs, and all were “fully monitored,” meaning all nesting attempts were monitored at these territories. During the monitoring period, 97 nests (49 in Seep sites and 48 in Reference sites) were monitored. Breeding productivity was similar at the Seep and Reference sites (2.7 and 3.3 young fledged per pair, respectively), although more pairs at Reference sites than Seep sites fledged at least one young (96 versus 76 percent, respectively). There were no other differences in breeding productivity between Seep site pairs and Reference site pairs. According to the best model, daily nest survival in 2022 was not related to whether the territory was in a Seep versus a Reference site. Completed nests at the Seep sites had similar fledging success as nests at Reference sites in 2022. At Seep sites, 56 percent of nests fledged young whereas 67 percent of Reference nests successfully fledged young. Predation was believed to be the primary source of nest failure at both sites. Predation accounted for 80 percent and 73 percent of nest failures at Seep and Reference sites, respectively. Failure of the remaining nests was attributed to infertile eggs and other unknown causes. Vireos placed their nests in 12 plant species in 2022. We detected no differences in nest placement between successful and unsuccessful vireo nests or between Seep and Reference sites. Precipitation appeared to play a role in fluctuations in the vireo population on MCBCP; however, it could not be directly linked to annual vireo breeding productivity. One possible factor that may be confounding the relationship between vireo breeding productivity and precipitation may be nest parasitism by Brown-headed Cowbirds ( Molothrus ater ) in the region, especially on the nearby San Luis Rey River.

California↗

USGS1972

Regional and other general factors bearing on evaluation of earthquake and other geologic hazards to coastal communities of southeastern Alaska

The great Alaska earthquake of March 27, 1964, brought into sharp focus the need for engineering geologic studies in seismically active regions. As a result, nine communities in southeastern Alaska were selected for reconnaissance investigations as an integral part of an overall program to evaluate earthquake and other geologic hazards in most of the larger Alaska coastal communities. This report gives background information on the regional and other general factors that bear on these evaluations. Southeastern Alaska, about 525 miles long and averaging about 125 miles in width, consists of a narrow mainland strip and numerous islands. For the most part, it is a region of rugged relief with numerous glaciers capping many of the higher mountainous areas and with long linear fiords forming the inland waterways. A maritime climate prevails with mild winters and cool summers. The southeastern part of the region receives the highest precipitation in the continental United States. Ketchikan, with a population of 6,994 in 1970, is the largest city. Geology and structure of the area are complex. Igneous, metamorphic, and sedimentary rocks crop out and range in age from Paleozoic to Tertiary. Surficial deposits of Pleistocene and Holocene age mantle many areas. All of southeastern Alaska, except probably the highest peaks, was covered by glacier ice advances of late Pleistocene age. Major deglaciation was well advanced by 10,000 years ago--a time which approximately marks the end of the Pleistocene and the beginning of the Holocene. There followed a period of warm climate called the Hypsithermal, which in southeastern Alaska began 7,000-8,000 years ago and ended about 4,800-3,500 years ago. Glaciers in most places receded back of their present positions. The Hypsithermal was followed by an interval (termed Neoglaciation) of cooler climate and resurgence of glacier ice which continues to the present, although most glaciers are now rapidly receding. During the past 10,000 years worldwide sea level has risen about 100 feet, but during the past 4,000 years it has risen only about 10 feet or about 0.03 inch per year. With sea level used as a datum, the amount of sea-level rise must be added to the apparent uplift of land for the time under consideration to determine the actual amount of land uplift. The widespread presence of emergent marine deposits, several hundred feet above sea level, demonstrates that the land in southeastern Alaska has been uplifted since the last major deglaciation. The greatest known has been uplifted since the last major deglaciation. The greatest known uplift is in the vicinity of Juneau where glaciomarine deposits are present 750 feet above present sea level. Part of southeastern Alaska is presently undergoing one of the most rapid rates of uplift of any place in the world. The fastest emergence is occurring in the Glacier Bay area where the land is being uplifted relative to sea level approximately 3.9 cm per year. Most or all of the uplift appears to be due to rebound as a result of deglaciation. Southeastern Alaska lies within the circum-Pacific earthquake belt, one of the world's greatest zones of seismic activity. During historic time, there have been five earthquakes in the region with magnitudes of 8 or greater, three with magnitudes of 7 to 8, eight with magnitudes of 6 to 7, more than 15 with magnitudes of 5 to 6, and about 140 recorded earthquakes with magnitudes smaller than 5 or of unassigned magnitudes. All of the earthquakes with magnitudes 8 or greater, and a large proportion of the others, appear to be related to the active Fairweather- Queen Charlotte Islands fault system or its western extension, the Chugach-St. Elias fault. Earthquake epicenters on the Denali fault system, the other major fault system in southeastern Alaska, are few in comparison. However, because high microearthquake activity has been recorded recently on this system and earthquakes of moderate size have occurred on some of its segments, the Denali fault system probably should not be dismissed as a relict fault system of no current tectonic importance. There are numerous other known faults, as well as lineaments that may be faults of varying degrees of tectonic activity in southeastern Alaska, adjacent Canada, and eastern Alaska. One of these elements is the Totschunda fault system, which connects with the Denali fault system in eastern Alaska; it has been very active during Holocene time but few historical earthquake epicenters appear to be related to it. Both historical seismicity and geologic conditions, such as frequency and recency of faulting, must be considered together to permit an assessment of the future earthquake probability of an area. Data are too few for both factors for an accurate evaluation to be made of earthquake probability in southeastern Alaska. However, information compiled in the form of strain-release and seismic-zone maps permit some generalizations. Thus, it is tentatively concluded that most, if not all, of southeastern Alaska should be placed in seismic zone 3, a zone in which earthquakes of magnitude greater than 6 will occur from time to time and where there may be major damage to manmade structures. Inferred effects from future earthquakes in southeastern Alaska include: (1) surface displacement along faults and other tectonic land-level changes, (2) ground shaking, (3) compaction, (4) liquefaction in cohesionless materials, (5) reaction of sensitive and quick clays, (6) water-sediment ejection and associated subsidence and ground fracturing, (7) earthquake-induced sub aerial slides and slumps, (8) earthquake induced subaqueous slides, (9) effects on glaciers and related features, (10) effects on ground water and stream flow, and (11) tsunamis, seiches, and other abnormal water waves. Because of the reconnaissance nature of our studies in the coastal communities and the sparsity of laboratory data on physical properties of geologic units in each area studied, the inferred effects must be largely empirical and generalized. Therefore, the inferences are based in large part upon the effects of past major earthquakes in Alaska and elsewhere, particularly upon the well-documented effects of the Alaska earthquake of March 27, 1964. Buildings, highways, bridges, tunnels, harbor facilities, pipelines, canals, and other manmade structures may be severely damaged or destroyed by fault displacement or related tectonic land-level changes in southeastern Alaska. Direct damage from fault rupture would be restricted virtually to structures built directly athwart the fault. In California and Nevada, fault rupture almost always accompanies shocks of magnitude 6.5 or greater. The Alaska earthquake of March 27, 1964, and the Chilean earthquake of May 22, 1960, dramatically illustrated the severe adverse effects that can result from uplift or subsidence over a wide area. The variable most responsible for the degree of shaking at any epicentral distance is the type of ground. Generally, shaking is considerably greater in poorly consolidated deposits than in hard bedrock, particularly if the deposits are water saturated. Severe shaking of alluvial deposits and manmade fill, with resultant heavy damage, is well documented from the records of many past earthquakes. Damage commonly has been heavy as a result of ground settlement caused by compaction of loose sediments by shaking during an earthquake. This has been especially true where compaction was accompanied by tectonic downdrop of land, such as occurred during the Chilean earthquake of 1960 and the Alaska earthquake of 1964. Loosely emplaced manmade fill, deltaic deposits, beach deposits, and alluvial deposits may be susceptible to compaction in southeastern Alaska during a severe earthquake. Liquefaction of sand and silt is a fairly common effect of large earthquakes. It was well illustrated at Niigata, Japan, during the earthquake of June 16, 1964, and resulted in extensive damage. When part of a sloping soil mass liquefies, the entire mass can undergo catastrophic failure and can flow as a high-density liquid. In southeastern Alaska, deltaic deposits probably would be most susceptible to liquefaction. Sensitive and quick clays, which lose a considerable part of their strength when shaken, commonly fail during an earthquake and become rapid earthflows. Extensive studies were made of the sensitivity of the Bootlegger Cove Clay at Anchorage because of the marked loss of shear strength and dramatic failures of the deposits during the Alaska earthquake of 1964. If similar sensitive clays are present in some places in southeastern Alaska, they most likely are in some of the emergent fine-grained marine deposits; supporting data to confirm their presence, however, are largely lacking. Records of some 50 major earthquakes show that in at least half of the instances water and sediment have been ejected from surficial deposits Water-sediment ejection and associated subsidence and ground fracturing commonly cause extensive damage to the works of man. Ejecta may fill basements and other low-lying parts of buildings. Agricultural land can be covered with a blanket of infertile soils, and small ponds can be filled or made shallow. In southeastern Alaska these phenomena are most likely to occur on valley floors, deltas, tidal flats, alluvial fans, swamps, and lakeshores. Earthquake-induced sliding on land generally is confined to steep slopes but may take place in fine-grained deposits on moderately to nearly flat surfaces if the deposits are subject to liquefaction. A large rockslide triggered by the Lituya Bay, Alaska, earthquake of July 10, 1958, generated a wave that surged up the opposite wall of the inlet to a record height of 1,740 feet. During the Hebgen Lake, Montana, earthquake of August 17, 1959, a spectacular rockslide plunged into the Madison River canyon, buried 28 people, dammed the river, and created a large lake. Earthquake-records are replete with accounts of sliding of surficial deposits during moderate to large earthquakes. Most or all of the general factors that favor subaerial landsliding are present in southeastern Alaska. Earthquake-induced subaqueous slides can produce adverse effects both nearshore and some distance offshore. Nearshore sliding may progress shoreward and destroy harbor facilities and other structures, commonly with substantial loss of life. Disastrous large submarine slides occurred along the fronts of deltas in Seward and Valdez during the Alaska earthquake of 1964. In similar fashion, the largest submarine slides in southeastern Alaska likely will be triggered along the larger delta fronts. Sliding farther offshore can constitute a threat to navigation because of changes in water depths. Also underwater sliding can break communication cables. Glaciers were not greatly affected by the Alaska earthquake of 1964 despite the fact that about 20 percent of the area that underwent strong shaking is covered by ice. In contrast, the cataclysmic avalanche of ice and rock that fell from a high glacier-covered peak in Peru during the earthquake of May 31, 1970, produced devastating effects downvalley on man and his works in the form of mudflows. Most towns in southeastern Alaska are sufficiently distant from glaciers so as not be to directly affected. Both the Alaska earthquake of 1964 and the Hebgen Lake, Montana, earthquake of 1959 significantly affected ground- and surface-water regimens. Water levels in some wells declined whereas in others flow increased. Some springs discharged at a rate three times as much as normal; flow of others decreased or stopped. Discharge of many streams increased markedly. Most or all of the effects described above could occur in parts of southeastern Alaska during future large earthquakes. Tsunamis, seiches, and other abnormal water waves associated with large earthquakes commonly cause vast property damage and heavy loss of life. Tsunami effects can be devastating to coastal areas as far as many thousands of miles from their generation source. Seiche effects generally are confined to inland bodies of water or to relatively enclosed coastal bodies of water. Abnormal waves generated by submarine sliding or by subaerial sliding into water generally produce only local effects but may be highly devastating. Tsunami waves resulting from the Chilean earthquake of 1960 inflicted extensive damage and loss of life on coastal communities throughout a large part of southern Chile, and significant runups and damage were recorded in many places throughout the Pacific Ocean area. The tsunami waves generated by the Alaska earthquake of 1964 struck with devastating force along a broad stretch of the Alaska coast and produced heavy property damage and loss of life as far away as Crescent City, Calif. Seiche waves generated by that earthquake reached runup heights of 20-30 feet on some lakes in Alaska, and water-level fluctuations were recorded on streams, reservoirs, lakes, and swimming pools in States bordering the Gulf of Mexico. Waves generated by submarine sliding struck violently at a number of places during or immediately after the quake and were the major cause of loss of life and damage to property. Slide-generated waves probably would have a higher destructive potential in southeastern Alaska than either tsunami waves or seiche waves because of their possibly higher local runups and because they can hit the shores almost without warning during or immediately after an earthquake. Nonearthquake-related geologic hazards, although generally far less dramatic than those related to earthquakes, tend to occur so much more frequently or persistently that their aggregate effects can be significant. Three kinds of geologic hazards of this type are discussed: (1) nonearthquake-induced landsliding and subaqueous sliding, (2) flooding, and (3) land uplift. The potential for nonearthquake-triggered landsliding in southeastern Alaska ranges widely from place to place. Past sliding generally furnishes the clue in the prediction of where and in what materials future sliding will occur. Fast-moving rockslides, debris slides, and mudflows can be expected to occur from time to time on steep slopes and be highly destructive to highways, power plants, pipelines, buildings, and other facilities located on a slope or at its base. Present slow downslope movement of talus can be expected to continue at the same general rate unless conditions are changed by man or there are climatic changes. Snow and debris avalanches can be especially hazardous during winter months. Long-inactive landslides may be triggered into renewed activity or new slides may be created by man-induced modifications. Accelerated slope erosion and debris flows may follow large-scale clearing and cutting of timber. Subaqueous sliding can be expected to occur periodically along fronts of deltas and on other oversteepened underwater slopes. Floods have been common in parts of southeastern Alaska because of heavy precipitation and rapid runoff from steep slopes with resulting heavy damage to roads and other facilities. Continued damage can be expected in the future unless more remedial measures are taken. Current uplift of land in southeastern Alaska, although probably not affecting man significantly in a short period of time, may have some adverse long-term effects. These long-term effects should be borne in mind when facilities such as docks and boat harbors are constructed on or near the shore, where there is a critical relation between height of land and water.

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USGS2024

Distribution, abundance, breeding activities, and habitat use of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2023 annual report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton, California (MCBCP or Base). Surveys for the Least Bell's Vireo were completed at MCBCP between April 11 and July 20, 2023. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed two to four times. We detected 561 territorial male vireos and 28 transient vireos in core survey areas. An additional 103 territorial male vireos and 15 transients were detected in non-core survey areas. Transient vireos were detected on 10 of the 15 drainages/sites surveyed (core and non-core areas). In core survey areas, 90 percent of vireo territories were on the four most populated drainages, with the Santa Margarita River containing 72 percent of all territories in core areas surveyed on Base. In core areas, 79 percent of male vireos were confirmed as paired; 69 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP decreased 2 percent from 2022. In two core survey area drainages, the number of territories increased by at least three, and in two core survey area drainages, the number of vireo territories decreased by at least four between 2022 and 2023. The number of vireo territories at the lower San Luis Rey River increased 2 percent from 2022, in contrast to the decrease at MCBCP; however, this change was negligible overall. Although the 10-percent decrease at Marine Corps Air Station, Camp Pendleton from 2022 to 2023 was superficially less trivial, this 10-percent decrease represented the loss of a single territory. The proportion of surveys during which Brown-headed Cowbirds ( Molothrus ater ) were detected decreased to 0.20 from a peak of 0.45 in 2022. Cowbirds were detected from April through July in 2023. Most core-area vireos (62 percent, including transients) used mixed willow ( Salix spp.) riparian habitat. An additional 7 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ) or Fremont cottonwoods ( Populus fremontii ). Riparian scrub dominated by mule fat ( Baccharis salicifolia ), sandbar willow ( S. exigua ), or blue elderberry ( Sambucus mexicana ) was used by 29 percent of vireos. Habitat dominated by coast live oak ( Quercus agrifolia ) and sycamore or non-native habitat was used by 1 percent of vireos; fewer than 1 percent of vireo territories were in upland scrub and habitat dominated by white alder ( Alnus rhombifolia ). In 2019, MCBCP began operating an artificial seep along the Santa Margarita River; then in 2021, two additional artificial seeps became operational. The artificial seeps pumped water to the surface starting in March and ending in August each year during daylight hours and were designed to increase the amount of surface water present to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited MCBCP, including the seep areas, within the past several years; therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents the fourth year of analyses of vireo and vegetation response to the artificial seeps. In 2020, we established four study sites along the Santa Margarita River, two surrounding and extending downstream of seep pumps at the Old Treatment Ponds and along Pump Road, and two Reference sites in similar habitat but further downstream of the Seep sites. In 2023, seep pumps at one Seep site did not function, and we recategorized that study site as Intermediate. Soil moisture was higher at sites that had surface water augmentation (Seep and Intermediate sites) than at the Reference site, and soil moisture also decreased with increasing distance from the seep pumps. We sampled vegetation at these sites to determine the effects of surface water enhancement by seep pumps. Soil moisture was positively related to total foliage cover, woody cover, and native herbaceous cover below 1 meter (m), and also positively related to native herbaceous cover between 1 and 2 m. The Seep site had greater total vegetation cover in the understory (71–79 percent) than the Intermediate (52–66 percent) and Reference (61–69 percent) sites. Total herbaceous cover below 3 m was higher at the Seep site than at the Intermediate site; total herbaceous cover between 1 and 3 m was higher at the Seep site than at the Reference sites. Native herbaceous cover below 3 m was greater at the Seep site than at the Reference sites; native herbaceous cover between 2 and 3 m was also greater at the Seep site than at the Intermediate site. Non-native cover below 3 m was greater at Seep and Reference sites than at the Intermediate site. We found no difference in woody cover among site types at any height. Vireo territory density among the Seep, Intermediate, and Reference sites was similar before the seep pumps were installed. However, vireo territory density at Seep and Intermediate sites combined was significantly higher than at Reference sites after the seep pumps were installed. The U.S. Geological Survey has been color banding Least Bell’s Vireos on Marine Corps Base Camp Pendleton since 1995. By the end of 2022, over 1,000 Least Bell’s Vireos had been color banded on Base. In 2023, we continued to color band and resight color banded Least Bell’s Vireos to evaluate adult survival, site fidelity, between-year movement, and the effect of surface water enhancement on vireo return rate, site fidelity, and between-year movement. We banded 180 Least Bell's Vireos for the first time during the 2023 season, including 1 adult vireo and 179 nestlings. Adult vireos were banded with unique color combinations, whereas nestlings were banded with a single gold numbered federal band on the right leg. We resighted 57 Least Bell's Vireos on Base in 2023 that had been banded before the 2023 breeding season, 20 of which we were unable to identify. Of the 37 that we could identify, 34 were banded on Base, 2 were originally banded on the San Luis Rey River, and 1 was banded at Marine Corps Air Station, Camp Pendleton. Adult birds of known age ranged from 1 to 8 years old. Base-wide survival of vireos was affected by sex, age, and year. Males had significantly higher annual survival than females. Adults had higher annual survival than first-year vireos. Survival for adults and first-year birds was lowest from 2020 to 2021 and highest from 2007 to 2008 and from 2012 to 2013. The return rate of adult vireos to Seep, Intermediate, or Reference sites was not affected by the original banding site (Seep versus Intermediate versus Reference). Most returning adult vireos, predominantly males, showed strong between-year site fidelity. Of the adults present in 2022, 88 percent (96 percent of males; 25 percent of females) returned in 2023 to within 100 m of their previous territory. The discrepancy between male and female return rates follows the pattern observed in previous years. The average between-year movement for returning adult vireos was 0.4±1.9 kilometers (km). The average movement of first-year vireos detected in 2023 that fledged from a known nest on MCBCP in 2022 was 0.9±0.5 km. We monitored Least Bell's Vireo pairs to evaluate the effects of surface water enhancement on nest success and breeding productivity. We monitored vireo nesting activity at 13 territories in the Seep site, 12 territories at the Intermediate site, and 25 territories in the Reference sites between April 8 and July 26. All territories except one at a Seep site and one at a Reference site were occupied by pairs, and all were fully monitored, meaning that all nesting attempts were monitored at these territories. During the monitoring period, 99 nests (26 in the Seep site, 28 at the Intermediate site, and 45 in Reference sites) were monitored. Breeding productivity was similar among Seep, Intermediate, and Reference sites (2.9, 3.6, and 3.0 young fledged per pair, respectively), and a similar percentage of pairs at Seep, Intermediate, and Reference sites fledged at least 1 young (83, 83, and 96 percent, respectively). Other measures of breeding productivity were also similar among Seep, Intermediate, and Reference site pairs. According to the best model, daily nest survival in 2023 was not related to site. Fledging success appeared lower at Intermediate and Seep sites than at the Reference sites in 2023 (48, 46, and 67 percent, respectively), although the difference was not statistically significant. Predation was believed to be the primary source of nest failure at all sites. Predation accounted for 85, 77, and 71 percent of nest failures at Seep, Intermediate, and Reference sites, respectively. Failure of the remaining nests was attributed to infertile eggs, collapse of the vegetation supporting the nest, and other unknown causes. We found no relationships between vireo productivity and understory (below 3 m) vegetation cover. Vireos placed their nests in 15 plant species in 2023. We found few differences in nest placement between successful and unsuccessful vireo nests. At Reference sites, successful vireo nests were placed slightly but significantly higher in the vegetation than unsuccessful nests, and at Intermediate sites, successful nests were placed significantly closer to the edge of the nest plant than unsuccessful nests. We did not find differences in nest placement among Seep, Intermediate, and Reference sites. We found that as bio-year precipitation increased, the number of fledglings produced per vireo pair also increased. We did not find a link between bio-year precipitation and adult survival.

California↗