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At least 1,387 records · Page 77Linked to original sources

USGS2015

Influence of in ovo mercury exposure, lake acidity, and other factors on common loon egg and chick quality in Wisconsin

A field study was conducted in Wisconsin (USA) to characterize in ovo mercury (Hg) exposure in common loons (Gavia immer). Total Hg mass fractions ranged from 0.17 mg/g to 1.23mg/g wet weight in eggs collected from nests on lakes representing a wide range of pH (5.0–8.1) and were modeled as a function of maternal loon Hg exposure and egg laying order. Blood total Hg mass fractions in a sample of loon chicks ranged from 0.84ug/g to 3.86 ug/g wet weight at hatch. Factors other than mercury exposure that may have persistent consequences on development of chicks from eggs collected on low-pH lakes (i.e., egg selenium, calcium, and fatty acid mass fractions) do not seem to be contributing to reported differences in loon chick quality as a function of lake pH. However, it was observed that adult male loons holding territories on neutral-pH lakes were larger on average than those occupying territories on low-pH lakes. Differences in adult body size of common loons holding territories on neutral-versus low-pH lakes may have genetic implications for differences in lake-source-related quality (i.e., size) in chicks. The tendency for high in ovo Hg exposure and smaller adult male size to co-occur in low-pH lakes complicates the interpretation of the relative contributions of each to resulting chick quality.

Wisconsin↗

USGS2000

Evaluation of planar halogenated and polycyclic aromatic hydrocarbons in estuarine sediments using ethoxyresorufin-O-deethylase induction of H4IIE cells

Polycyclic aromatic hydrocarbons (PAHs) and planar halogenated hydrocarbons (PHHs), including polychlorinated dibenzo- p -dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were determined in fractionated sediment extracts from the Hudson-Raritan estuary and Newark Bay, New Jersey, USA, as part of a comprehensive risk assessment. Contributions of PCDDs/PCDFs, PCBs, and PAHs to the total toxic equivalents (TEQs) were measured using an H4IIE bioassay and calculated from instrumentally determined concentrations using international toxic equivalency factors. The H4IIE TEQs of whole and fractionated extracts were compared to calculated TEQs to investigate the applicability of the bioassay approach for evaluating 7-ethoxyresorufin- O -deethylease induction by PHHs and PAHs present together in complex mixtures. Although 2,3,7,8-tetrachloro-dibenzo- p -dioxin contributed from 41 to 79% of the calculated TEQs from PCDDs/PCDFs and planar PCBs in all sediments sampled, the PAH-containing fractions accounted for >80% of the total TEQs determined either instrumentally or by bioassay. Calculated TEQs from PAHs, based on reported toxic equivalency factors for only seven PAHs, were severalfold greater than the bioassay-derived TEQs of PAH-only fractions of the sediment extracts. Significant correlations were observed between bioassay and instrumentally determined toxic equivalents in the more purified fractions but not in fractions only purified by size-exclusion or argentate chromatographies alone.

Environmental Toxicology and Chemistry↗

USGS2001

Frequently co‐occurring pesticides and volatile organic compounds in public supply and monitoring wells, southern New Jersey, USA

One or more pesticides were detected with one or more volatile organic compounds (VOCs) in more than 95% of samples collected from 30 public supply and 95 monitoring wells screened in the unconsolidated surficial aquifer system of southern New Jersey, USA. Overall, more than 140,000 and more than 3,000 unique combinations of pesticides with VOCs were detected in two or more samples from the supply and monitoring wells, respectively. More than 400 of these combinations were detected in 20% or more of the samples from the supply wells, whereas only 17 were detected in 20% or more of the samples from the monitoring wells. Although many constituent combinations detected in water from the supply and monitoring wells are similar, differences in constituent combinations also were found and can be attributed, in part, to differences in the characteristics of these two well types. The monitoring wells sampled during this study yield water that typically was recharged beneath a single land‐use setting during a recent, discrete time interval and that flowed along relatively short paths to the wells. Public supply wells, in contrast, yield large volumes of water and typically have contributing areas that are orders of magnitude larger than those of the monitoring wells. These large contributing areas generally encompass multiple land uses; moreover, because flow paths that originate in these areas vary in length, these wells typically yield water that was recharged over a large temporal interval. Water withdrawn from public supply wells, therefore, contains a mixture of waters of different ages that were recharged beneath various land‐use settings. Because public supply wells intercept water flowing along longer paths with longer residence times and integrate waters from a larger source area than those associated with monitoring wells, they are more likely to yield water that contains constituents that were used in greater quantities in the past, that were introduced from point sources, and/or that are derived from the degradation of parent compounds along extended flow paths.

New Jersey↗

USGS2011

Bioaccumulation dynamics and exposure routes of Cd and Cu among species of aquatic mayflies

Consumption of periphyton is a potentially important route of metal exposure to benthic invertebrate grazers. The present study examined the bioaccumulation kinetics of dissolved and dietary Cd and Cu in five species of mayflies (class Insecta). Artificial stream water and benthic diatoms were separately labeled with enriched stable metal isotopes to determine physiological rate constants used by a biokinetic bioaccumulation model. The model was employed to simulate the effects of metal partitioning between water and food, expressed as the bioconcentration factor (BCF), as well as ingestion rate (IR) and metal assimilation efficiency of food (AE), on the relative importance of water and food to metal bioaccumulation. For all test species, the contribution of dietary uptake of Cd and Cu increased with BCF. For a given BCF, the contribution of food to the body burden increased with k uf , the metal uptake rate constant from food that combined variation in IR and AE. To explore the relative importance of water and diet exposure routes under field conditions, we used estimated site‐specific aqueous free‐ion concentrations to model Cd and Cu accumulation from aqueous exposure, exclusively. The predicted concentrations accounted for less than 5% of the observed concentrations, implying that most bioaccumulated metal was acquired from food. At least for the taxa considered in this study, we conclude that consumption of metal‐contaminated periphyton can result in elevated metal body burdens and potentially increase the risk of metal toxicity.

Environmental Toxicology and Chemistry↗

USGS2020

Fishing for food: Quantifying recreational fisheries harvest in Wisconsin lakes

Recreational fisheries have high economic worth, valued at US$190 billion globally. An important, but underappreciated, secondary value of recreational catch is its role as a source of food. This contribution is poorly understood due to difficulty in estimating recreational harvest at spatial scales beyond a single system, as traditionally estimated from individual creel surveys. Here, we address this gap using 28‐year creel surveys of ~300 Wisconsin inland lakes. We develop a statistical model of recreational harvest for individual lakes and then scale‐up to unsurveyed lakes (3,769 lakes; 73% of statewide lake surface area). We generate a statewide estimate of recreational lake harvest of ~4,200 metric tons and an estimated annual angler consumption rate of ~1.1 kg, nearly equal to the total estimated United States per capita freshwater fish consumption. An important ecosystem service, recreational harvest makes significant contributions to human diets and plays an often‐unheralded role in food security.

Wisconsin↗

USGS2014

Water's Way at Sleepers River watershed – revisiting flow generation in a post-glacial landscape, Vermont USA

The Sleepers River Research Watershed (SRRW) in Vermont, USA, has been the site of active hydrologic research since 1959 and was the setting where Dunne and Black demonstrated the importance and controls of saturation-excess overland flow (SOF) on streamflow generation. Here, we review the early studies from the SRRW and show how they guided our conceptual approach to hydrologic research at the SRRW during the most recent 25 years. In so doing, we chronicle a shift in the field from early studies that relied exclusively on hydrometric measurements to today's studies that include chemical and isotopic approaches to further elucidate streamflow generation mechanisms. Highlights of this evolution in hydrologic understanding include the following: (i) confirmation of the importance of SOF to streamflow generation, and at larger scales than first imagined; (ii) stored catchment water dominates stream response, except under unusual conditions such as deep frozen ground; (iii) hydrometric, chemical and isotopic approaches to hydrograph separation yield consistent and complementary results; (iv) nitrate and sulfate isotopic compositions specific to atmospheric inputs constrain new water contributions to streamflow; and (v) convergent areas, or ‘hillslope hollows’, contribute disproportionately to event hydrographs. We conclude by summarizing some remaining challenges that lead us to a vision for the future of research at the SRRW to address fundamental questions in the catchment sciences.

Vermont↗

USGS2015

Regional variability in dust-on-snow processes and impacts in the Upper Colorado River Basin

Dust deposition onto mountain snow cover in the Upper Colorado River Basin frequently occurs in the spring when wind speeds and dust emission peaks on the nearby Colorado Plateau. Dust loading has increased since the intensive settlement in the western USA in the mid 1880s. The effects of dust-on-snow have been well studied at Senator Beck Basin Study Area (SBBSA) in the San Juan Mountains, CO, the first high-altitude area of contact for predominantly southwesterly winds transporting dust from the southern Colorado Plateau. To capture variability in dust transport from the broader Colorado Plateau and dust deposition across a larger area of the Colorado River water sources, an additional study plot was established in 2009 on Grand Mesa, 150 km to the north of SBBSA in west central, CO. Here, we compare the 4-year (2010–2013) dust source, deposition, and radiative forcing records at Grand Mesa Study Plot (GMSP) and Swamp Angel Study Plot (SASP), SBBSA's subalpine study plot. The study plots have similar site elevations/environments and differ mainly in the amount of dust deposited and ensuing impacts. At SASP, end of year dust concentrations ranged from 0.83 mg g −1 to 4.80 mg g −1 , and daily mean spring dust radiative forcing ranged from 50–65 W m −2 , advancing melt by 24–49 days. At GMSP, which received 1.0 mg g −1 less dust per season on average, spring radiative forcings of 32–50 W m −2 advanced melt by 15–30 days. Remote sensing imagery showed that observed dust events were frequently associated with dust emission from the southern Colorado Plateau. Dust from these sources generally passed south of GMSP, and back trajectory footprints modelled for observed dust events were commonly more westerly and northerly for GMSP relative to SASP. These factors suggest that although the southern Colorado Plateau contains important dust sources, dust contributions from other dust sources contribute to dust loading in this region, and likely account for the majority of dust loading at GMSP.

Hydrological Processes↗

USGS2016

Synthesis of soil-hydraulic properties and infiltration timescales in wildfire-affected soils

We collected soil-hydraulic property data from the literature for wildfire-affected soils, ash, and unburned soils. These data were used to calculate metrics and timescales of hydrologic response related to infiltration and surface runoff generation. Sorptivity ( S ) and wetting front potential (Ψ f ) were significantly different (lower) in burned soils compared with unburned soils, whereas field-saturated hydraulic conductivity ( K fs ) was not significantly different. The magnitude and duration of the influence of capillarity during infiltration was greatly reduced in burned soils, causing faster ponding times in response to rainfall. Ash had large values of S and K fs but moderate values of Ψ f , compared with unburned and burned soils, indicating ash has long ponding times in response to rainfall. The ratio of S 2 /K fs was nearly constant (~100 mm) for unburned soils but more variable in burned soils, suggesting that unburned soils have a balance between gravity and capillarity contributions to infiltration that may depend on soil organic matter, whereas in burned soils the gravity contribution to infiltration is greater. Changes in S and K fs in burned soils act synergistically to reduce infiltration and accelerate and amplify surface runoff generation. Synthesis of these findings identifies three key areas for future research. First, short timescales of capillary influences on infiltration indicate the need for better measurements of infiltration at times less than 1 min to accurately characterize S in burned soils. Second, using parameter values, such as Ψ f , from unburned areas could produce substantial errors in hydrologic modeling when used without adjustment for wildfire effects, causing parameter compensation and resulting underestimation of K fs . Third, more thorough measurement campaigns that capture soil-structural changes, organic matter impacts, quantitative water repellency trends, and soil-water content along with soil-hydraulic properties could drive the development of better techniques for numerically simulating infiltration in burned areas.

Hydrological Processes↗

USGS2001

Chemical and isotopic evidence of nitrogen transformation in the Mississippi River, 1997-98

Nitrate (NO 3 ) and other nutrients discharged by the Mississippi River are suspected of causing a zone of depleted dissolved oxygen (hypoxic zone) in the Gulf of Mexico each summer. The hypoxic zone may have an adverse affect on aquatic life and commercial fisheries. The amount of NO 3 delivered by the Mississippi River to the Gulf of Mexico is well documented, but the relative contributions of different sources of NO 3 , and the magnitude of subsequent in-stream transformations of NO 3 , are not well understood. Forty-two water samples collected in 1997 and 1998 at eight stations located either on the Mississippi River or its major tributaries were analysed for NO 3 , total nitrogen (N), atrazine, chloride concentrations and NO 3 stable isotopes (δ 15 N and δ 18 O). These data are used to assess the magnitude and nature of in-stream N transformation and to determine if the δ 15 N and δ 18 O of NO 3 provide information about NO 3 sources and transformation processes in a large river system (drainage area 2 900 000 km 2 ) that would otherwise be unavailable using concentration and discharge data alone. Results from 42 samples indicate that the δ 15 N and δ 18 O ratios between sites on the Mississippi River and its tributaries are somewhat distinctive, and vary with season and discharge rate. Of particular interest are two nearly Lagrangian sample sets, in which samples from the Mississippi River at St Francisville, LA, are compared with samples collected from the Ohio River at Grand Chain, II, and the Mississippi River at Thebes, IL. In both Lagrangian sets, mass-balance calculations indicate only a small amount of in-stream N loss. The stable isotope data from the samples suggest that in-stream N assimilation and not denitrification accounts for most of the N loss in the lower Mississippi River during the spring and early summer months.

Illinois, Iowa, Kentucky, Louisiana, Mississippi, ↗

USGS2006

Interactions between groundwater and surface water in a Virginia coastal plain watershed. 2. Acid-base chemistry

A field study of surface water and groundwater interactions during baseflow and stormflow conditions was performed at the Reedy Creek watershed in the Virginia Coastal Plain. Three estimates of the average saturated hydraulic conductivity ( K s ) of the unconfined aquifer were in reasonable agreement (ranging from 0.0033 to 0.010 cm/s), indicating that baseflow in the creek is entirely from the drainage of shallow groundwater from the relatively thin (1–6 m thick) unconfined aquifer. This relatively permeable surficial aquifer was found to be underlain by dark, olive grey, clay-silt and diatomaceous Miocene deposits of low permeability known as the Calvert Formation, which is believed to function as a confining bed in the area. A chemical hydrograph separation technique was used to resolve the contributions of [old] (pre-event) and [new] (event) water to stormflow. Results from a major rainstorm indicated that old water dominated the stormflow response of the watershed, although the new water contribution approached 40% at the hydrograph peak. Stormflow at Reedy Creek appears to result from saturation overland flow from variable source areas which include the stream channels and a significant part of the riparian wetland area. This response appears to be attributable to the transient dynamics of the shallow groundwater flow system and to the formation of localized groundwater mounds which raise the water-table to the wetland surface.

Hydrological Processes↗

USGS2007

The application of electrical conductivity as a tracer for hydrograph separation in urban catchments

Two-component hydrograph separation was performed on 19 low-to-moderate intensity rainfall events in a 4.1-km2 urban watershed to infer the relative and absolute contribution of surface runoff (e.g. new water) to stormflow generation between 2001 and 2003. The electrical conductivity (EC) of water was used as a continuous and inexpensive tracer, with order of magnitude differences in precipitation (12-46 ??S/cm) and pre-event streamwater EC values (520-1297 ??S/cm). While new water accounted for most of the increased discharge during storms (61-117%), the contribution of new water to total discharge during events was typically lower (18-78%) and negatively correlated with antecedent stream discharge (r2 = 0??55, p < 0??01). The amount of new water was positively correlated with total rainfall (r2 = 0??77), but hydrograph separation results suggest that less than half (9-46%) of the total rainfall on impervious surfaces is rapidly routed to the stream channel as new water. Comparison of hydrograph separation results using non-conservative tracers (EC and Si) and a conservative isotopic tracer (??D) for two events showed similar results and highlighted the potential application of EC as an inexpensive, high frequency tracer for hydrograph separation studies in urban catchments. The use of a simple tracer-based approach may help hydrologists and watershed managers to better understand impervious surface runoff, stormflow generation and non-point-source pollutant loading to urban streams. Copyright ?? 2007 John Wiley & Sons, Ltd.

Hydrological Processes↗

USGS2011

Influence of a thin veneer of low-hydraulic-conductivity sediment on modelled exchange between river water and groundwater in response to induced infiltration

A thin layer of fine‐grained sediment commonly is deposited at the sediment–water interface of streams and rivers during low‐flow conditions, and may hinder exchange at the sediment–water interface similar to that observed at many riverbank‐filtration (RBF) sites. Results from a numerical groundwater‐flow model indicate that a low‐permeability veneer reduces the contribution of river water to a pumping well in a riparian aquifer to various degrees, depending on simulated hydraulic gradients, hydrogeological properties, and pumping conditions. Seepage of river water is reduced by 5–10% when a 2‐cm thick, low‐permeability veneer is present on the bed surface. Increasing thickness of the low‐permeability layer to 0·1 m has little effect on distribution of seepage or percentage contribution from the river to the pumping well. A three‐orders‐of‐magnitude reduction in hydraulic conductivity of the veneer is required to reduce seepage from the river to the extent typically associated with clogging at RBF sites. This degree of reduction is much larger than field‐measured values that were on the order of a factor of 20–25. Over 90% of seepage occurs within 12 m of the shoreline closest to the pumping well for most simulations. Virtually no seepage occurs through the thalweg near the shoreline opposite the pumping well, although no low‐permeability sediment was simulated for the thalweg. These results are relevant to natural settings that favour formation of a substantial, low‐permeability sediment veneer, as well as central‐pivot irrigation systems, and municipal water supplies where river seepage is induced via pumping wells.

Colorado↗

USGS2011

Annual estimates of water and solute export from 42 tributaries to the Yukon River

Annual export of 11 major and trace solutes for the Yukon River is found to be accurately determined based on summing 42 tributary contributions. These findings provide the first published estimates of tributary specific distribution of solutes within the Yukon River basin. First, we show that annual discharge of the Yukon River can be computed by summing calculated annual discharges from 42 tributaries. Annual discharge for the tributaries is calculated from the basin area and average annual precipitation over that area using a previously published regional regression equation. Based on tributary inputs, we estimate an average annual discharge for the Yukon River of 210 km 3  year –1 . This value is within 1% of the average measured annual discharge at the U.S. Geological Survey gaging station near the river terminus at Pilot Station, AK, for water years 2001 through 2005. Next, annual loads for 11 solutes are determined by combining annual discharge with point measurements of solute concentrations in tributary river water. Based on the sum of solutes in tributary water, we find that the Yukon River discharges approximately 33 million metric tons of dissolved solids each year at Pilot Station. Discharged solutes are dominated by cations calcium and magnesium (5.65 × 10 9 and 1.42 × 10 9  g year –1 ) and anions bicarbonate and sulphate (17.3 × 10 9 and 5.40 × 10 9  g year –1 ). These loads compare well with loads calculated independently at the three continuous gaging stations along the Yukon River. These findings show how annual solute yields vary throughout a major subarctic river basin and that accurate estimates of total river export can be determined from calculated tributary contributions.

Hydrological Processes↗

USGS2013

Lidar-derived estimate and uncertainty of carbon sink in successional phases of woody encroachment

Woody encroachment is a globally occurring phenomenon that contributes to the global carbon sink. The magnitude of this contribution needs to be estimated at regional and local scales to address uncertainties present in the global- and continental-scale estimates, and guide regional policy and management in balancing restoration activities, including removal of woody plants, with greenhouse gas mitigation goals. The objective of this study was to estimate carbon stored in various successional phases of woody encroachment. Using lidar measurements of individual trees, we present high-resolution estimates of aboveground carbon storage in juniper woodlands. Segmentation analysis of lidar point cloud data identified a total of 60,628 juniper tree crowns across four watersheds. Tree heights, canopy cover, and density derived from lidar were strongly correlated with field measurements of 2613 juniper stems measured in 85 plots (30 × 30 m). Aboveground total biomass of individual trees was estimated using a regression model with lidar-derived height and crown area as predictors (Adj. R 2 = 0.76, p < 0.001, RMSE = 0.58 kg). The predicted mean aboveground woody carbon storage for the study area was 677 g/m 2 . Uncertainty in carbon storage estimates was examined with a Monte Carlo approach that addressed major error sources. Ranges predicted with uncertainty analysis in the mean, individual tree, aboveground woody C, and associated standard deviation were 0.35 – 143.6 kg and 0.5 – 1.25 kg, respectively. Later successional phases of woody encroachment had, on average, twice the aboveground carbon relative to earlier phases. Woody encroachment might be more successfully managed and balanced with carbon storage goals by identifying priority areas in earlier phases of encroachment where intensive treatments are most effective.

Idaho↗

USGS2015

Climate change and water resources in a tropical island system: Propagation of uncertainty from statistically downscaled climate models to hydrologic models

Many tropical islands have limited water resources with historically increasing demand, all potentially affected by a changing climate. The effects of climate change on island hydrology are difficult to model due to steep local precipitation gradients and sparse data. This work uses 10 statistically downscaled general circulation models (GCMs) under two greenhouse gas emission scenarios to evaluate the uncertainty propagated from GCMs in projecting the effects of climate change on water resources in a tropical island system. The assessment is conducted using a previously configured hydrologic model, the Precipitation Runoff Modelling System (PRMS) for Puerto Rico. Projected climate data and their modelled hydrologic variables versus historical measurements and their modelled hydrologic variables are found to have empirical distribution functions that are statistically different with less than 1 year of daily data aggregation. Thus, only annual averages of the projected hydrologic variables are employed as completely bias‐corrected model outputs. The magnitude of the projected total flow decreases in the four regions covering Puerto Rico, but with a large range of uncertainty depending on the makeup of the GCM ensemble. The multi‐model mean projected total flow decreases by 49–88% of historical amounts from the 1960s to the 2090s for the high emissions scenarios and by 39–79% for the low emissions scenarios. Subsurface flow contributions decreased the least and groundwater flow contributions decreased the most across the island. At locations critical to water supply for human use, projected streamflow is shown to decrease substantially below projected withdrawals by 2099.

Puerto Rico↗

USGS2012

Varying sediment sources (Hudson Strait, Cumberland Sound, Baffin Bay) to the NW Labrador Sea slope between and during Heinrich events 0 to 4

Core HU97048-007PC was recovered from the continental Labrador Sea slope at a water depth of 945 m, 250 km seaward from the mouth of Cumberland Sound, and 400 km north of Hudson Strait. Cumberland Sound is a structural trough partly floored by Cretaceous mudstones and Paleozoic carbonates. The record extends from ∼10 to 58 ka. On-board logging revealed a complex series of lithofacies, including buff-colored detrital carbonate-rich sediments [Heinrich (H)-events] frequently bracketed by black facies. We investigate the provenance of these facies using quantitative X-ray diffraction on drill-core samples from Paleozoic and Cretaceous bedrock from the SE Baffin Island Shelf, and on the < 2-mm sediment fraction in a transect of five cores from Cumberland Sound to the NW Labrador Sea. A sediment unmixing program was used to discriminate between sediment sources, which included dolomite-rich sediments from Baffin Bay, calcite-rich sediments from Hudson Strait and discrete sources from Cumberland Sound. Results indicated that the bulk of the sediment was derived from Cumberland Sound, but Baffin Bay contributed to sediments coeval with H-0 (Younger Dryas), whereas Hudson Strait was the source during H-events 1–4. Contributions from the Cretaceous outcrops within Cumberland Sound bracket H-events, thus both leading and lagging Hudson Strait-sourced H-events.

Hudson Strait;Cumberland Sound;Baffin Bay↗

USGS2018

Spatial distribution of band recoveries of black brant

On average, band recovery rates of adult black brant ( Branta bernicla nigricans ) more than doubled between the 2000s and 2010s. However, the spatial distribution of band recoveries of black brant has not been reported. Our objective was to describe the spatial distribution of band recoveries of black brant since 1990. We found that Alaska, California, and Mexico accounted for ≥89% of band recoveries for black brant released from the Arctic and the Tutakoke River Colony in southwestern Alaska, in each decade studied. Although recovery rates increased in each major harvest region from the 1990s to 2010s, increases were not even. For brant released from the Arctic, the recovery rate in Alaska has gone up 7‐fold, whereas the recovery rate in Mexico has increased 1.3‐fold since the 1990s. For brant banded in the Arctic, the increased recovery rates in Alaska resulted largely from a rise in recoveries from the Izembek Lagoon area. For brant banded at the Tutakoke River Colony, the recovery rate in Alaska increased 4.8‐fold, whereas recovery rates in Mexico increased 1.6‐fold. Despite the reduced relative contribution of Mexico to band recoveries in the 2010s, Bahia San Quintin, Mexico, still contributes more recoveries than any other wintering estuary. Because 57–60% of black brant band recoveries occur at the localities of Izembek Lagoon, Alaska; Humboldt Bay, California; and Bahia San Quintin, it is likely that accurate annual estimates of the black brant population using Lincoln's method could be derived from hunter bag checks at these 3 areas. If population managers are interested in managing harvest rates of black brant, they could focus efforts on the main hunting areas we highlight in this paper. Finally, it is unclear if the recent increases in band recovery rates are the result of increased harvest, a declining population, or both; therefore, we suggest refinement of population monitoring programs and continued monitoring of band recovery rates.

Journal of Wildlife Management↗

USGS2020

Canada goose survival and recovery rates in urban and rural areas of Iowa, USA

Once extirpated from much of their North American range, temperate-breeding Canada geese ( Branta canadensis maxima ) have reached high abundance. As a result, focus has shifted from restoration to managing harvest and addressing human-goose conflict. Conflict persists or is increasing in urban areas throughout the Mississippi Flyway. Managers need more information regarding demographic rates to determine how hunting affects geese breeding in urban areas and what management actions may be required to achieve management goals. We estimated survival, dead recovery, live recapture, and fidelity probabilities using data from 77,872 Canada geese banded in Iowa, USA, during 1999–2019 using Burnham joint live-dead band recovery models. Factors predicted to affect parameters in candidate models included age (juvenile, subadult, adult), banding site (urban, rural), time, trend, harvest regulation index, and winter severity index. We predicted Canada geese banded in urban areas would have higher survival and lower dead recovery rates than geese banded at rural sites. The top model indicated support for age and banding site effects, and trends in survival and recovery rate (Brownie parameterization). Adult survival was similar for urban (0.75; range = 0.60–0.92) and rural (0.75; range = 0.66–0.82) geese and relatively constant across years. Mean juvenile survival was lower in urban (0.74; range = 0.48–0.93) than rural (0.85; range = 0.68–0.92) areas. Survival increased for urban-banded juveniles and recovery rates increased during liberalization of harvest regulations and decreased after regulations stabilized. Recovery rates of subadults increased for the urban and rural groups. Our results suggest Canada geese breeding in urban areas contribute to harvest and specialized regulations can affect these populations. Harvest regulations in place during our analysis may not have reached a threshold required to observe substantial changes in survival. Current human-goose conflict in urban areas suggests survival has not decreased to a level required to completely address conflict via reduction in goose abundance. Managers may consider additional liberalization of harvest regulations and monitoring via banding to determine to what degree hunter harvest contributes to reducing human-goose conflict and what additional management actions will be required to achieve goals. © 2020 The Wildlife Society.

Iowa↗