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USGS2022

Restoration of Gavia immer (common loon) in Minnesota—2021 annual report

The Deepwater Horizon oil spill caused extensive injury to natural resources in the Gulf of Mexico, and Gavia immer (common loon) were negatively affected from the spill. The Open Ocean Trustee Implementation Group funded the project Restoration of Common Loons in Minnesota to restore common loons lost to the spill. In 2020–21, priority lakes in an eight-county region in north-central Minnesota were identified to focus project activities. In 2021, surveys on these lakes were started to monitor common loon territory occupancy, nest success, and chick survival. We surveyed 62 lakes and identified 110 common loon territories that will be included in the project. At least 1 nest attempt was observed in 78 of 110 territories, and a second nest attempt was observed in 23 territories. A third nest attempt was observed in one territory. Successful nesting was observed in 32 of 110 territories. We present no formal data analysis and plan to analyze the data after the collection of all field data in subsequent years.

Minnesota↗

USGS2022

Growth, survival, and cohort formation of juvenile Lost River (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) in Upper Klamath Lake, Oregon, and Clear Lake Reservoir, California—2020 monitoring report

Executive Summary Populations of federally endangered Lost River ( Deltistes luxatus ) and shortnose suckers ( Chasmistes brevirostris ) in Upper Klamath Lake, Oregon, and Clear Lake Reservoir (hereinafter, Clear Lake), California, are experiencing long-term decreases in abundance. Upper Klamath Lake populations are decreasing not only because of adult mortality, which is relatively low, but also because they are not being balanced by recruitment of young adult suckers into known adult spawning aggregations. Long-term monitoring of juvenile sucker populations is conducted to (1) determine if there are annual and species-specific differences in production, survival, and growth, (2) better understand when juvenile sucker mortality is greatest, and (3) help identify potential causes of high juvenile sucker mortality particularly in Upper Klamath Lake. The U.S. Geological Survey (USGS) monitoring program, begun in 2015, tracks cohorts through summer months and among years in Upper Klamath and Clear Lakes. Data on juvenile suckers captured in trap nets are used to provide information on annual variability in age-0 sucker apparent production, juvenile sucker apparent survival, apparent growth, species composition, and health. Upper Klamath Lake indices of year-class strength suggest that the 2020 age-0 cohort is one of the lowest since standardized monitoring began. Despite apparently low over-winter survival, the relatively large 2019 cohort persisted in our 2020 samples and continues to contribute to the populations. Although the 2019 cohort age-0 suckers were composed mainly of Lost River suckers, the age-1 suckers from the 2019 cohort were mainly shortnose suckers. Lost River suckers comprised the largest proportion of the 2020 year-class and were only captured in July and August. Shortnose suckers were mainly captured in August and September and comprised a smaller proportion of the 2020 year-class. Age distribution of suckers captured in Clear Lake indicates greater juvenile survival than in Upper Klamath Lake. Most juvenile suckers captured were age-3 and age-4 suckers classified as the combination of Klamath largescale suckers ( Catostomus snyderi ) and shortnose suckers from the Lost River Basin, from the 2016 and 2017 cohorts. A lack of age-0 suckers captured in Clear Lake during years with the low inflow or lake levels initially lead us to believe that low water prevented spawning and year class formation. However, recent data indicate that some cohorts that were not captured as age-0 suckers were detected in later years at age-1 or age-2. This finding indicates that juvenile suckers in Clear Lake may spend one or more years in the tributaries or that sampling efficacy for age-0 suckers varies among years because of water depth. The first 5 years of this monitoring program indicated different patterns in recruitment and survival of juvenile suckers between Upper Klamath and Clear Lakes. Since the monitoring program began in 2015, age-0 sucker catch rates, interpreted as indices of year-class strength, were greatest in Upper Klamath Lake in 2016 and 2019. In those years Lost River suckers made up the majority of age-0 sucker catches; however, in 2017 and 2020 the age-1 sucker catches from these cohorts were mainly composed of shortnose suckers or suckers with genetic markers of both Klamath largescale and shortnose suckers, indicating a low overwinter survival for Lost River suckers even when the age-0 catches were high. Age-0 suckers do not fully recruit to our sampling gear in Upper Klamath Lake until August, experience high mortality by September, and are almost undetectable by the following July or August in most years. In Clear Lake, suckers frequently are not captured until age-1 or age-2 and annual survival appears much greater.

California, Oregon↗

USGS2023

Least Bell's Vireos and Southwestern Willow Flycatchers at the San Luis Rey Flood Risk Management Project Area in San Diego County, California—Breeding activities and habitat use—2022 annual report

Executive Summary We completed four protocol surveys for Least Bell’s Vireos ( Vireo bellii pusillus ; vireo) during the breeding season, supplemented by weekly territory monitoring visits. We identified a total of 133 territorial male vireos; 114 were confirmed as paired, and 3 were confirmed as single males. For the remaining 16 territories, we were unable to confirm breeding status. Two transient vireos were detected in 2022. The vireo population in the Project Area increased by 9 percent from 2021 to 2022. The vireo population at Marine Corps Base Camp Pendleton also increased (4 percent), whereas the population at Marine Corps Air Station remained relatively stable (decreased from 10 pairs to 9) and the Otay River population decreased by 10 percent (2 territories). We used an index of treatment (Treatment Index) to evaluate the effect of on-going vegetation clearing on the Project Area vireo population. The Treatment Index measures the cumulative effect of vegetation treatment within a territory (since 2005) by using the percentage area treated weighted by the number of years since treatment. We determined that the Treatment Index for unoccupied habitat was more than four times that of occupied habitat, indicating that vireos selected habitat that was less treated in which to settle. We monitored vireo nests at three general site types: (1) within the flood channel where exotic and native vegetation removal has occurred regularly (Channel), (2) three sites near the flood channel where limited exotic and native vegetation removal has occurred (Off-channel), and (3) three sites that have been actively restored by planting native vegetation (Restoration). Nesting activity was monitored in 80 territories, 3 of which were occupied by single males and 1 by a male whose breeding status could not be confirmed. Overall, 38 percent of completed nests were successful and nest success did not differ among the three sites. In 2022, there were no differences with regard to clutch size, hatching, or fledging success among Channel, Off-channel and Restoration sites. Overall breeding success and productivity were slightly higher in 2022 than in 2021, with 72 percent of pairs fledgling at least one young and pairs fledging an average of 2.2±1.7 young. To investigate if the cumulative years of treatment had an effect on vireo reproductive effort, we looked at the effects of the Treatment Index on reproductive parameters. Results from generalized linear models indicated that treatment did not have an effect on vireo nesting effort or the number of vireo fledglings per pair produced in 2022. Similarly, we did not detect an effect of Treatment Index on daily survival rate (DSR) of nests. Analysis of vegetation data collected at vireo nests from 2006 to 2022 did not reveal an effect of vegetation cover at the nest on DSR. We did find, however, that Channel nests were placed higher in the host plant than Off-channel nests. In the Channel and Off-channel sites, successful nests were placed closer to the edge of the host plants than unsuccessful nests. Additionally, successful Off-channel nests were placed lower in the vegetation, in shorter host plants, and closer to the edge of the vegetation clump than unsuccessful nests. Red/arroyo willow ( Salix laevigata or Salix lasiolepis ) were the species most commonly selected for nesting by vireos in all three site types. Black willow ( Salix gooddingii ) and mule fat ( Baccharis salicifolia ) also were commonly used. Vireos used a wider variety of species for nesting in Channel and Off-channel sites (eight and six species, respectively) compared to Restoration sites (two species), although there was limited nesting in Restoration sites in 2022. There were 43 vireos banded before the 2022 breeding season that were resighted and identified at the Project Area in 2022, all of which were originally banded in the Project Area. Adult birds of known age ranged from 1 to 7 years old. A total of 146 vireos were newly banded in 2022. There were 8 adult vireos banded with a unique color combination, and 138 nestlings were banded with a single dark blue numbered federal band on the left leg. Between 2006 and 2022, survivorship of males (66±11 percent) was consistently higher than that of females (59±12 percent). First-year birds from 2006 to 2022 had an average annual survivorship of 15±6 percent. First-year dispersal in 2022 averaged 6.7±7.4 kilometers (km), with the longest dispersal (15.3 km) by a male that was recaptured at Fallbrook Creek, Fallbrook Naval Weapons Station (FNWS). From 2007 to 2011, most returning first-year vireos returned to the Project Area, whereas from 2014 to 2016, the majority of returning birds dispersed to areas outside of the Project Area. From 2018 to 2021, the trend shifted, and more first-year vireos returned to the Project area. In 2022, only one first-year vireo returned to the project area and two dispersed to sites outside the Project Area (upstream to the middle San Luis Rey River and to Fallbrook Creek, FNWS). However, the total number of identified first-year vireos was low and the trend in 2022 will likely shift as additional returning first-year vireos are identified in subsequent years. Most of the returning adult male vireos showed strong between-year site fidelity to their previous territories. Seventy-three percent of males (27/37) occupied a territory in 2022 that they had defended in 2021 (within 100 meters [m]). There were no females (0/4) detected in 2022 that returned to a territory they occupied in 2021; however, 50 percent of females (2/4) detected in 2022 returned to areas adjacent to their previous territories (within 300 m). The average between-year movement for returning adult vireos was 0.3±0.7 km. The amount of treatment at adults’ 2021 territories did not affect the distance adults moved to their 2022 territories. We completed four protocol surveys for the endangered Southwestern Willow Flycatcher ( Empidonax traillii extimus ; flycatcher) at the Project Area between May 16 and July 25, 2022. Four transient Willow Flycatchers were detected in the Project Area in 2022. Two transients were detected in Reach 1, one in Reach 3a, and one in Pilgrim Pond. There were not any resident flycatchers documented in the Project Area in 2022. A total of 46 vegetation transects (528 points) were sampled at the Project Area in 2022. Seventy-one percent (378/528) of points were located in the Channel, and 22 percent (115/528) were in Upper Pond. The remaining 7 percent (35/528) of points were at the Whelan Restoration site. Foliage cover below 2 m was higher at the Channel points compared to Upper Pond and Whelan Restoration, which can be attributed to the dense herbaceous vegetation that grows after mowing. Above 2 m, foliage cover was similar at the Channel and Whelan Restoration sites and was higher than at Upper Pond. Average canopy height was higher in the Channel (5.6±3.4 m) compared to Upper Pond (4.7±2.9 m) and Whelan Restoration (4.6±1.9 m). From 2006 to 2022, total foliage cover declined above 2 m in the Channel, in contrast to Upper Pond and Whelan Restoration, where little directional change in vegetation cover has occurred and where vegetation cover has largely recovered to 2006 levels. Within the Channel, the steepest declines occurred between 2009 and 2013 and between 2014 and 2016. Since 2016, we observed an increase in foliage cover, largely herbaceous, between 0 and 2 m within the Channel. The percent cover remained below levels detected before 2009 for other height classes. We sampled vegetation at 44 vireo nests and 44 random plots (“territory” plots) within territories in the Channel and Upper Pond after the 2022 breeding season. Vireos in the Channel established territories in areas with significantly more cover from 3 to 6 m but less cover below 2 m relative to the available habitat. Within territories, Channel vireos selected nest sites with significantly more foliage cover from 2 to 3 m. Vireos at Upper Pond established territories in areas with significantly more foliage cover from 5 to 6 m and below 1 m relative to available habitat. However, within territories, Upper Pond vireos selected nest sites with significantly less foliage cover from 5 to 6 m and below 1 m. Data either are not available or have limited availability owing to restrictions of the funding entity (U.S. Army Corps of Engineers). Please contact Christopher Chabot, Planning Division, Los Angeles District, U.S. Army Corps of Engineers, for more information.

Califoria↗

USGS2024

Distribution, abundance, and breeding activities of the Southwestern Willow Flycatcher at Marine Corps Base Camp Pendleton, California—2022 annual report

California↗

USGS2024

Distribution, Abundance, and Breeding Activities of the Southwestern Willow Flycatcher at Marine Corps Base Camp Pendleton, California—2020 Annual Report

Executive Summary Surveys for the endangered Southwestern Willow Flycatcher ( Empidonax traillii extimus ) were done at Marine Corps Base Camp Pendleton (MCBCP or “Base”), California, between May 4 and July 31, 2020. All of MCBCP’s historically occupied riparian habitat (core survey area) was surveyed for flycatchers in 2020. Additionally, one-fifth of the unoccupied riparian habitat (non-core survey area) was surveyed for flycatchers. Thirteen transient Willow Flycatchers of unknown subspecies were observed on four of the seven drainages surveyed in 2020. No Willow Flycatchers were detected at Fallbrook Creek, Pilgrim Creek, or San Mateo Creek. Transients occurred in a range of habitat types, including mixed willow ( Salix spp.) riparian, riparian scrub, willow-sycamore ( Platanus racemosa ) or willow-cottonwood ( Populus fremontii ) dominated riparian vegetation, and upland scrub. Exotic vegetation, primarily poison hemlock ( Conium maculatum ), was present in most flycatcher locations. The resident population of Southwestern Willow Flycatchers on MCBCP declined 33 percent from three individuals in 2019 to two individuals in 2020. In 2020, the resident Southwestern Willow Flycatcher population on Base consisted of one male and one female. No single males or non-territorial floaters were observed in 2020. Overall, one territory was established consisting of one monogamous pair. Resident flycatchers were restricted to the Santa Margarita River, and distribution was limited to the Pueblitos breeding area. All resident flycatchers were located in mixed willow riparian habitat. Nesting was initiated in late May and continued into early August. Three nesting attempts were documented, of which 33 percent (1/3) were successful. Predation and substrate failure accounted for the two nest failures. Two fledglings were produced, yielding a seasonal productivity of two young/pair. No instances of Brown-headed Cowbird ( Molothrus ater ) parasitism were observed. Flycatchers placed nests in two plant species: native sandbar willow ( Salix exigua ) and exotic poison hemlock. One hundred percent of resident birds that were present at MCBCP in 2020 were banded in previous years; no unbanded birds were detected. Of the three uniquely banded adult flycatchers present during the 2019 breeding season, 100 percent (1/1) of males and 50 percent (1/2) of females returned to MCBCP in 2020, and both banded flycatchers returned to the same breeding area they occupied in 2019. None of the seven nestlings banded in 2019 returned to MCBCP in 2020, and none were detected off Base. Six nestlings from two nests were banded in 2020; only two survived to fledging. From 2000 to 2020, overall adult survival of Southwestern Willow Flycatchers on MCBCP was 60 percent, while first-year survival was 20 percent. A conspecific attraction study initiated on Base in 2018 and repeated annually through 2020 found that 100 percent of breeding flycatchers detected in 2020 settled close to automated playback units.

California↗

USGS2024

Bees of the Buenos Aires National Wildlife Refuge—A preliminary report on a bee survey in a vulnerable semi-desert grassland of the Sonoran Desert

Pollinators are vital to the continued existence and seed production of about 87.5 percent of all flowering plants (Ollerton and others, 2011). In the semi-desert grasslands of Buenos Aires National Wildlife Refuge, in the Sonoran Desert of the United States, flowering forbs provide seed vital to the food base of wildlife, including the 136 species of resident and migratory birds using the Refuge’s grasslands and, notably, the endangered Colinus virginianus ridgwayi (masked bobwhite quail) for which the Refuge was established. The Sonoran Desert is known for its high diversity of native bees, but these pollinators have not been extensively described at the Refuge. We conducted a survey of native bees at the Refuge from late May 2019 through early February 2020. Of all bees collected, we subsampled, curated, and identified over 3,300 bees representing 39 genera within four families (Andrenidae, Apidae, Halictidae, Megachilidae). For about 8 percent of the sampled bees, we further identified 36 species and several potentially new, undescribed species using either visual or deoxyribonucleic acid (DNA) barcoding methods. Sampling was done using bee bowls and blue-vane traps. Our initial results suggest the Refuge is species rich in native bees and supports diverse bee faunas across subtle differences in plant composition and location within the Refuge. Continued survey, inventory, and focused monitoring of the bee populations of the Refuge will be valuable in understanding the relationship of bee populations with the health and productivity of seed-bearing plants, effect of prescribed fire on bee fauna, the ongoing dynamics of bee-plant interactions, and how the bee pollinator community of the Refuge is responding to stressors, such as invasive species proliferation and changing climate conditions.

Arizona↗

USGS2024

Least Bell's Vireos and Southwestern Willow Flycatchers—Breeding activities and habitat use—2023 annual report

Executive Summary We completed four protocol surveys for Least Bell’s Vireos ( Vireo bellii pusillus ; hereinafter vireo) during the breeding season, supplemented by weekly territory monitoring visits between April 6 and July 20 at the San Luis Rey Flood Risk Management Project Area (hereinafter Project Area). We identified a total of 136 territorial male vireos; 121 were confirmed as paired, and 4 were confirmed as single males. For the remaining 11 territories, we were unable to confirm breeding status. In 2023, two transient vireos were detected. The vireo population in the Project Area increased by 2 percent from 2022 to 2023. Populations in southern San Diego County also increased (by 6 percent on the Otay River) or were stable (Salt Creek/Wolf Canyon). In contrast, the vireo population at Marine Corps Base Camp Pendleton (MCBCP) and at Marine Corps Air Station decreased by 2 and 10 percent, respectively. We used an index of treatment (hereinafter Treatment Index) to evaluate the effect of ongoing vegetation clearing on the Project Area vireo population. The Treatment Index measures the cumulative effect of vegetation treatment within a territory by using the percentage area treated weighted by the number of years since treatment. We determined that the Treatment Index for an unoccupied habitat was more than four times higher than that of an occupied habitat, indicating that vireos selected habitats that were less treated in which to settle. We monitored vireo nests at three general site types: (1) within the flood channel where non-native and native vegetation removal has occurred regularly (hereinafter Channel), (2) three sites near the flood channel where limited non-native and native vegetation removal has occurred (hereinafter Off-channel), and (3) three sites that have been actively restored by planting native vegetation (hereinafter Restoration). Nesting activity was monitored in 84 territories, 4 of which were occupied by single males. Overall, 46 percent of completed nests were successful, and nest success did not differ among the three sites. In 2023, we found that territories in the Channel had greater hatching success per egg compared to Off-channel, but there were no other differences with regard to clutch size, hatching, or fledging success among Channel, Off-channel, and Restoration sites. Overall breeding success and productivity were slightly higher in 2023 than in 2022, with pairs fledging an average±standard deviation of 3.1±2.1 young and 79 percent of pairs fledging at least 1 young. To investigate if the cumulative years of treatment had an effect on vireo reproductive effort, we looked at the effects of the Treatment Index on reproductive parameters. Results from generalized linear models indicated that treatment did not have an effect on vireo nesting effort (the number of nest attempts) or the number of vireo fledglings per pair produced in 2023. Similarly, we did not detect an effect of Treatment Index on the daily survival rate (DSR) of nests. Analysis of vegetation data collected at vireo nests from 2006 to 2023 did not reveal an effect of vegetation cover at the nest on DSR. We did find, however, that Channel nests were placed higher in and farther from the edge of the host plant than Off-channel nests. Within sites, we did not detect any differences in vegetation cover between successful and unsuccessful nests. Red/arroyo willow ( Salix laevigata or Salix lasiolepis ) and mule fat ( Baccharis salicifolia ) were the species most commonly selected for nesting by vireos in all three site types. Black willow ( Salix gooddingii ) and sandbar willow ( Salix exigua ) also were commonly used. Vireos used a wider variety of species for nesting in Channel and Off-channel sites (10 and 13 species, respectively) compared to Restoration sites (2 species), although there was limited nesting in Restoration sites in 2023. There were 51 vireos banded before the 2023 breeding season that were resighted and identified at the Project Area in 2023. Two of these vireos were originally banded outside of the Project Area, at the Santa Margarita River on MCBCP. Adult birds of known age ranged from 1 to 7 years old. Between 2006 and 2023, survival of males (66±11 percent) was consistently higher than that of females (60±12 percent). First-year birds from 2006 to 2022 had an average annual survival of 15±5 percent. First-year dispersal in 2023 averaged 20.2±31.3 kilometers (km), with the longest dispersal (76.3 km) by a female that was recaptured at Wolf Canyon, a tributary to Otay River. From 2007 to 2012, most returning first-year vireos returned to the Project Area, whereas from 2014 to 2016, a greater proportion of returning birds dispersed to areas outside of the Project Area. From 2018 to 2022, the trend shifted, and more first-year vireos returned to the Project Area, except for 2022 when only one out of five first-year vireos returned to the Project Area. This trend continued in 2023: 71 percent of all first-year vireos returned to the Project Area, and 29 percent dispersed to areas outside of the Project Area (San Diego River and Wolf Canyon). Most of the returning adult male vireos showed strong between-year fidelity to their previous territories. In 2023, 94 percent of males (34/36) occupied a territory that they had defended in 2022 (within 100 meters [m]). In 2023, 33 percent of females (1/3) detected returned to a territory they occupied in 2022. The average between-year movement for returning adult vireos was 0.2±0.9 km. The amount of treatment at adults’ 2022 territories did not affect the distance adults moved to their 2023 territories. We completed four protocol surveys for the endangered Southwestern Willow Flycatcher ( Empidonax traillii extimus ; hereinafter flycatcher) at the Project Area between May 15 and July 21, 2023. In 2023, four transient Willow Flycatchers were detected in the Project Area. Two transients were detected in Reach 1, one in Reach 3a, and one in Whelan Mitigation. No resident flycatchers were documented in the Project Area in 2023. A total of 46 vegetation transects (516 points) were sampled in the Project Area in 2023. There were 71 percent (368/516) of points located in the Channel, and 22 percent (113/516) were in Upper Pond. The remaining 7 percent (35/516) of points were at the Whelan Restoration site. Foliage cover below 1 m was higher at the Channel points and Upper Pond compared to Whelan Restoration. From 1 to 3 m, foliage cover was similar at all 3 sites; however, above 3 m foliage cover was higher in the Channel compared to the Upper Pond and Whelan Restoration sites. Average canopy height was higher in the Channel (5.6±3.8 m) compared to Upper Pond (4.7±2.7 m) and Whelan Restoration (4.0±2.0 m). From 2006 to 2023, total foliage cover declined from 2 to 3 m and above 6 m in the Channel, in contrast to Upper Pond and Whelan Restoration, where little directional change in vegetation cover has occurred and where vegetation cover has largely recovered to 2006 levels. Within the Channel, the steepest declines occurred between 2009 and 2013 and between 2014 and 2016. Since 2016, we observed an increase in foliage cover, largely herbaceous, between 0 and 2 m within the Channel. Although increases were observed at all height classes after 2016, percentage cover has remained below levels measured before 2009. We sampled vegetation at 45 vireo nests and 45 random plots (territory plots) within territories in the Channel and Upper Pond after the 2023 breeding season. Vireos in the Channel established territories in areas with significantly more cover from 3 to 7 m but less cover below 1 m relative to the available habitat. Within territories, Channel vireos selected nest sites largely at random, but with significantly less foliage cover from 4 to 5 m. Vireos at Upper Pond established territories in areas with significantly more foliage cover below 4 m and from 5 to 6 m relative to available habitat. Within territories, Upper Pond vireos also selected nest sites at random except for a preference for sites with significantly less foliage cover below 1 m.

Open-File Report↗

USGS2024

State of science, gap analysis, and prioritization for southeastern United States water-quality impacts from coastal storms—Fiscal year 2023 program report to the Water Resources Mission Area from the Water Availability Impacts of Extreme Events Program—Hurricanes

Tropical cyclones (coastal storm events that include tropical depressions, tropical storms, and hurricanes) cause landscape-scale disturbances that can lead to impaired water quality and thus reduce water availability for use. Stakeholders and scientists at local and national scales have illustrated a need for understanding these risks to water quality. A regional and comprehensive understanding of the impacts of tropical storms and hurricanes on surface-water and groundwater quality—and thus water availability—is lacking for potentially impacted coastal and inland areas. As the U.S. Geological Survey considers development of tools to predict the extent to which water-quality impacts of hurricanes affect water availability, an assessment of the state of the science of hurricane impacts is needed, including a gap analysis and prioritization of data and science needs. This assessment focuses on the southeastern coastal States.

southeastern United States↗

USGS2026

Restoration of Gavia immer (common loon) in Minnesota—2025 annual report

In cooperation with the Minnesota Department of Natural Resources, the U.S. Geological Survey monitored 98 Gavia immer (common loon) focal territories and 43 nonfocal territories in north-central Minnesota in 2025. Focal territories are those sampling units from which study inferences can be made. Nonfocal territories were adjacent to focal territories and were observed to monitor common loon dynamics across an entire waterbody. In collaboration with lake associations and private citizens, we deployed 44 artificial nesting platforms to 44 focal territories, called treatment territories. Territorial surveys to monitor occupancy, nesting, and chick survival were completed between April 27 and August 14, 2025. We attempted to visit each focal and nonfocal territory once per week. At least 1 nest attempt was observed in 40 of 54 control territories and 37 of 44 treatment territories. In treatment territories, 14 nests were on an artificial nesting platform, and the remaining nests were on natural substrates. Chicks or other evidence of hatching were observed in 20 of 54 control territories (37 percent) and 28 of 44 treatment territories (64 percent). Twelve of those successful nests in treatment territories were on artificial nesting platforms.

Minnesota↗

USGS1934

Preliminary geological report on the Salt Plains reservoir site, Oklahoma

Following a request from the U.S. Bureau of Biological Survey, the writer was assigned by the Director of the U.S. Geological Survey to make a preliminary geological investigation of the Salt Plains area in Oklahoma. He spent the period from January 13 to January 22, 1934, in the field making this study. (available as photostat copy only)

Open-File Report↗

USGS1939