Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Bird Conservation”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
USGS2021

Decision-support framework for linking regional-scale management actions to continental-scale conservation of wide-ranging species

Anas acuta (Northern pintail; hereafter pintail) was selected as a model species on which to base a decision-support framework linking regional actions to continental-scale population and harvest objectives. This framework was then used to engage stakeholders, such as Landscape Conservation Cooperatives’ (LCCs’) habitat management partners within areas of importance to pintails, while maximizing cross-taxa effects from the framework. The mathematical framework for the model had been previously developed for pintails. A key assumption incorporated into the model is that density dependence in survival occurs during the post-hunting (winter) period, where resources are hypothesized to be limiting. Because few data are available to directly inform this process, the approach used was to build a hierarchical Bayesian integrated population model (IPM) that simultaneously uses data from bird-band recoveries, breeding population counts, and harvest surveys to estimate values of parameters of an annual population projection model, including population size, survival rate, reproductive rate, and process and observation error variances, that are logically consistent with each other, given the mathematical structure imposed through the IPM. The main accomplishments of this study are (1) development of an IPM for pintail to guide harvest and habitat management, (2) development of a Prairie Parkland Region breeding submodel to predict pintail productivity, (3) development of statistical methodology to estimate pintail productivity (as measured by the ratio of juvenile to adults in hunter-collected wing samples) and winter survival and to relate these estimates to covariates, and (4) illustration of how to use a model and estimated parameter values to predict pintail population size and sustainable harvest as a function of habitat. Estimation of pintail survival from bird-banding data shows that there has been relatively little variation in survival over the period 1960–2013. A productivity model showed strong effects of breeding ground conditions, wintering-ground precipitation, and density dependence on pintail productivity. Thus, most temporal variation in pintail demographic rates has been due to effects on reproduction and not survival, including effects of breeding or wintering-ground habitat. These results indicate that habitat conservation efforts may be most effective if they focus on maintaining or increasing breeding and wintering-ground habitat to increase pintail productivity rather than pintail survival. Environmental perturbations in excess of historical experience, such as what could occur under climate change, might have meaningful effects on survival but cannot be estimated with current data. Direct effects of climate, land use, or management are likely to be greater on productivity than survival, but substantial uncertainty remains about predictions of equilibrium population size and sustainable yield.

Open-File Report↗
USGS2021

Marine distribution and foraging habitat highlight potential threats at sea for Endangered Bermuda Petrel Pterodroma cahow

Marine spatial planning relies on detailed spatial information of marine areas to ensure effective conservation of species. To enhance our understanding of marine habitat use by the highly pelagic Bermuda petrel Pterodroma cahow , we deployed GPS tags on 6 chick-rearing adults in April 2019 and constructed a habitat suitability model using locations classified as foraging to explore functional responses to a selection of marine environmental variables. We defined 15 trips for 5 individuals, ranging from 1-6 trips per bird, that included both short and long foraging excursions indicative of a dual foraging strategy that optimizes chick feeding and self maintenance. The maximum distance birds flew from Bermuda during foraging trips ranged from 61 to 2513 km (total trip lengths: 186-14051 km). Behaviourally deduced foraging habitat was best predicted at shorter distances from the colony, under warmer sea surface temperature, greater sea surface height, and in deeper water compared to transiting locations; our model results indicated that suitable foraging habitat exists beyond the core home range of the population, as far north as the highly productive Gulf Stream frontal system, and within the territorial waters of both the USA and Canada. Our results are crucial to inform management decisions and international conservation efforts by better identifying potential threats encountered at sea by this globally rare seabird and highlighting jurisdictions potentially responsible for mitigating those threats.

Nonsuch Island, Horn Rock↗
USGS2021

Characterization of water-resource threats and needs for U.S. Fish and Wildlife Service National Wildlife Refuges in the Legacy Mountain-Prairie Region, 2020

The U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service (FWS), began a study in 2019 to complete the compilation and quality assurance of water-resource threats and needs data for the 117 National Wildlife Refuges (NWRs) in the FWS Legacy Mountain-Prairie Region (LMPR) and to characterize the water-resource threats and needs of each refuge and of the LMPR itself. The LMPR encompasses the states of Colorado, Kansas, Montana, Nebraska, North Dakota, South Dakota, Utah, and Wyoming. This report includes the compilation and quality assurance of current (April 2020) water-resource threats and needs data for the refuges in the LMPR and a statistical, graphical, and spatial characterization, including the ranking and prioritization of threat types, threat causes, and needs by the number of occurrences in the LMPR as a whole and by refuges, states, and select U.S. Environmental Protection Agency Level III Ecoregions. A total of 540 unique threat occurrences were identified for 109 refuges in the LMPR. No threats were identified for eight refuges. About 43 percent of the threat occurrences, for 59 refuges, had a high-severity threat rating. Of the 10 most common threat types, 8 were also among the most common high-severity threat types. Water-resource threats had 72 different causes. About 83 percent of the overall common causes for threats and for high-severity threats were the same. The most common threat types overall and the most common high-severity threat types were compromised water management capability, habitat shifting/alteration, and altered flow regimes. The 20 water-resource threat types for Long Lake NWR were the most for refuges in the LMPR. Other refuges with the greatest number of threat types included Marais des Cygnes NWR (18) and Arapaho and Lee Metcalf NWRs (16 each). About 54 percent of refuges with threats had high-severity threats. Arapaho and Quivira NWRs each had 10 high-severity threat types, the maximum number of high-severity threat types for LMPR refuges. A total of 637 unique need occurrences were identified for 114 refuges. No needs were reported for three refuges. The most common need type, a Water Resource Inventory and Assessment, was reported for 78 refuges. Two of the most common need types, repair and replace water management infrastructure and water supply/quantity monitoring, were the most common high-priority need types. Bear River Migratory Bird Refuge had the most (39) unique water-resource need types for refuges in the LMPR. Other refuges with the greatest number of need types were Baca (38), Alamosa (36), and Monte Vista (36) NWRs. The most high-priority need types for a refuge was 23, at Monte Vista NWR. Alamosa (22), Baca (22), and Lake Andes (19) NWRs were also among the top 4 refuges with the greatest number of high-priority need types. An overall ranking scheme was developed to identify refuges that have the highest-ranking priority for conservation efforts to fulfill refuges’ statutory purposes. The count of occurrences of high-severity threats and high-priority needs were summed to determine the overall ranking value for a refuge. The 10 refuges with the highest overall ranking values, in order of ranking from higher to lower, were Alamosa, Baca, and Monte Vista NWRs (tied for highest); Lake Andes NWR, Ouray and Quivira NWRs, Bear River Migratory Bird Refuge and Flint Hills NWR, Cokeville Meadows NWR, and Arapaho NWR. About 33 percent of overall threat occurrences were reported as under the control of the FWS to mitigate, as were 37 percent of all threat occurrences with a high-severity rating. The most common overall threat types and high-severity threat types under FWS control were compromised water management capability; habitat shifting/alteration; altered flow regimes; loss/alteration of wetland habitat; and legal challenges or fines for non-compliance with water policy, law, or regulation. A total of 68 percent of overall need occurrences and 67 percent of all high-priority need occurrences were under the control of the FWS. The most common overall need types and high-priority needs types under control were repair or replace water management infrastructure, water supply/quantity monitoring, water quality baseline monitoring, and protect habitat from invasive species. A Water Resource Inventory and Assessment was also a common overall need under FWS control, as was the high-priority need of water level monitoring.

Colorado, Kansas, Montana, Nebraska, North Dakota,↗
USGS2025

Fine-scale spatial risk models to predict avian collisions with power lines

1. Avian fatalities caused by collisions with overhead power lines are an important conservation issue worldwide. Although mitigation strategies can help reduce mortalities, given their considerable cost and the vast scale of power line infrastructure, cost-effective action requires that these efforts be prioritised to areas with the highest potential risk to birds. To date, this risk assessment has usually been guided by potentially biased information on the location of recorded fatalities. 2. Here we use five years of GPS tracking data from endangered Tasmanian wedge-tailed eagles to develop an alternative approach to risk assessment: fine-scale spatial risk models based on behavioural analyses. We built and cross-validated a model that generates spatially explicit predictions of the probability that eagles would cross power lines at hazardous altitudes throughout the entire Tasmanian electricity distribution network. 3. In our model, probability of power line crossings was most strongly associated with the proportion of forest edges, wet forest, open habitat, freshwater sources, and rural residential developments in the area surrounding the power lines. Cross-validation indicated that the model effectively predicted where Tasmanian wedge-tailed eagles cross power lines at low altitude. 4. Model validation suggested our approach was a powerful predictor of the locations of power line collisions involving eagles. The locations of almost all (94%) confirmed eagle fatalities were in the half of the total Tasmanian power line area assigned the higher risk by the model, and 50% of incidents occurred in the 30% of the power line area estimated to be highest risk. 5. Synthesis and applications . Our study illustrates a framework for using bird movement data to provide insights into avian behaviour and the risk they encounter around power line infrastructure. Electricity delivery industries can use these models to identify the electrical infrastructure that poses the highest risk to avian survival and prioritise mitigation efforts, thereby optimizing the benefit of investments to reduce detrimental effects on biodiversity. Our model can direct pre-emptive mitigation across Tasmania’s 20,310 km of distribution infrastructure to meet management targets aiming to reduce the negative effects of power lines on the Tasmanian wedge-tailed eagle.

Tasmania↗
USGS2011

Migration patterns, use of stopover areas, and austral summer movements of Swainson's hawks

From 1995 to 1998, we tracked movements of adult Swainson's Hawks ( Buteo swainsoni ), using satellite telemetry to characterize migration, important stopover areas, and movements in the austral summer. We tagged 46 hawks from July to September on their nesting grounds in seven U.S. states and two Canadian provinces. Swainson's Hawks followed three basic routes south on a broad front, converged along the east coast of central Mexico, and followed a concentrated corridor to a communal area in central Argentina for the austral summer. North of 20° N, southward and northward tracks differed little for individuals from east of the continental divide but differed greatly (up to 1700 km) for individuals from west of the continental divide. Hawks left the breeding grounds mid-August to mid-October; departure dates did not differ by location, year, or sex. Southbound migration lasted 42 to 98 days, northbound migration 51 to 82 days. Southbound, 36% of the Swainson's Hawks departed the nesting grounds nearly 3 weeks earlier than the other radio-marked hawks and made stopovers 9.0–26.0 days long in seven separate areas, mainly in the southern Great Plains, southern Arizona and New Mexico, and north-central Mexico. The birds stayed in their nonbreeding range for 76 to 128 days. All used a core area in central Argentina within 23% of the 738 800-km 2 austral summer range, where they frequently moved long distances (up to 1600 km). Conservation of Swainson's Hawks must be an international effort that considers habitats used during nesting and non-nesting seasons, including migration stopovers.

The Condor↗
USGS2019

Impacts to wildlife of wind energy siting and operation in the United States

Electricity from wind energy is a major contributor to the strategy to reduce greenhouse gas emissions from fossil fuel use and thus reduce the negative impacts of climate change. Wind energy, like all power sources, can have adverse impacts on wildlife. After nearly 25 years of focused research, these impacts are much better understood, although uncertainty remains. In this report, we summarize positive impacts of replacing fossil fuels with wind energy, while describing what we have learned and what remains uncertain about negative ecological impacts of the construction and operation of land-based and offshore wind energy on wildlife and wildlife habitat in the U.S. Finally, we propose research on ways to minimize these impacts. TO SUMMARIZE: 1 Environmental and other benefits of wind energy include near-zero greenhouse gas emissions, reductions of other common air pollutants, and little or no water use associated with producing electricity from wind energy. Various scenarios for meeting U.S. carbon emission reduction goals indicate that a four- to five-fold expansion of land-based wind energy from the current 97 gigawatts (GW) by the year 2050 is needed to minimize temperature increases and reduce the risk of climate change to people and wildlife. 2 Collision fatalities of birds and bats are the most visible and measurable impacts of wind energy production. Current estimates suggest most bird species, especially songbirds, are at low risk of population-level impacts. Raptors as a group appear more vulnerable to collisions. Population-level impacts on migratory tree bats are a concern, and better information on population sizes is needed to evaluate potential impacts to these species. Although recorded fatalities of cave-dwelling bat species are typically low at most wind energy facilities, additional mortality from collisions is a concern given major declines in these species due to white-nose syndrome (WNS). Assessments of regional and cumulative fatality impacts for birds and bats have been hampered by the lack of data from areas with a high proportion of the nation’s installed wind energy capacity. Efforts to expand data accessibility from all regions are underway, and this greater access to data along with improvements in statistical estimators should lead to improved impact assessments. 3 Habitat impacts of wind energy development are difficult to assess. An individual wind energy facility may encompass thousands of acres, but only a small percentage of the landscape within the project area is directly transformed. If a project is sited in previously undisturbed habitat, there is concern for indirect impacts, such as displacement of sensitive species. Studies to date indicate displacement of some species, but the long-term population impacts are unknown. 4 Offshore wind energy development in the U.S. is just beginning. Studies at offshore wind facilities in Europe indicate some bird and marine mammal species are displaced from project areas, but substantial uncertainty exists regarding the individual or population-level impacts of this displacement. Bird and bat collisions with offshore turbines are thought to be less common than at terrestrial facilities, but currently the tools to measure fatalities at offshore wind energy facilities are not available. The wind energy industry, state and federal agencies, conservation groups, academia, and scientific organizations have collaborated for nearly 25 years to conduct the research needed to improve our understanding of risk to wildlife and to avoid and minimize that risk. Efforts to reduce the uncertainty about wildlife risk must keep up withthe pace and scale of the need to reduce carbon emissions. This will require focusing our research priorities and increasing the rate at which we incorporate research results into the development and validation of best practices for siting and operating wind energy facilities.

Issues in Ecology↗
USGS2022

Pink-footed Shearwater Ardenna creatopus

The Pink-footed Shearwater’s life history is tied to the Humboldt and California upwelling currents in the Eastern Pacific Ocean. It is larger than other shearwaters in its range, other than Flesh-footed Shearwater Ardenna carneipes. It is also distinct in appearance with pinkish bill and feet, pale underparts, and brown to grayish upperparts. It is known to breed on the Juan Fernández Islands and Isla Mocha, off central Chile. Birds spend the non-breeding period in waters off Peru and northward to waters off the west coast of North America. Breeding occurs in colonies, where pairs nest in burrows and the female lays a single egg. Breeding colonies generally are located on steep slopes in both open and forested habitats. During the breeding period, the species forages mainly in waters over the relatively narrow continental shelf as well as over deep offshore waters, depending on breeding colony. During the non-breeding period, individuals concentrate near the continental shelf-break and slope, and in more pelagic waters while making migratory movements. The Pink-footed Shearwater preys on fish and squid by seizing them at the surface or by making shallow dives. Foraging is often in association with albacore, dolphins, other seabirds, and fishing vessels. Pink-footed Shearwater is listed as Vulnerable by the IUCN and Endangered by Chile and Canada. Principal conservation threats are mortality from fisheries bycatch (especially in South American fisheries), and predation and habitat degradation from introduced mammals on breeding islands.

Birds of the World↗
USGS2016

Factors affecting wetland connectivity for wintering semipalmated sandpipers ( Calidris pusilla ) in the Caribbean

Wetland connectivity provides migratory shorebirds varying options to meet energy requirements to survive and complete their annual cycle. Multiple factors mediate movement and residency of spatially segregated wetlands. Information on these factors is lacking in the tropics, yet such information is invaluable for conservation design. The influence of seven biotic and abiotic factors on local movement and residency rates of Semipalmated Sandpipers ( Calidris pusilla ) among three major wetlands in southwestern Puerto Rico in 2013–2014 was assessed using multi-state models. The model with highest support (AIC c w i = 0.78) indicated that weekly residency rates increased seasonally, and were positively influenced by bird abundance and the interaction of prey density and rainfall. Movement rates were negatively influenced by inter-wetland distance, which varied annually, ranging from 0.01 ± 0.004 to 0.33 ± 0.08. Age class (adult, juvenile), extent of shoreline habitat (km), and body condition (estimated percent fat) did not influence residency rates (95% CIs overlapped Betas). Our findings indicated that coastal wetlands in southwestern Puerto Rico were connected, pointing at the joint value of salt flats and mangroves for overwintering Semipalmated Sandpipers. Connectivity between different types of wetlands likely widens resource diversity, which is essential for coping with unpredictable environments. Additional work is needed to generalize our understanding of inter-wetland dynamics and their potential benefits to inform shorebird conservation strategies in the Caribbean.

Puerto Rico↗
USGS2007

Diversity, origins and virulence of Avipoxviruses in Hawaiian Forest Birds

We cultured avian pox (Avipoxvirus spp.) from lesions collected on Hawai'i, Maui, Moloka'i, and 'Oahu in the Hawaiian Islands from 15 native or non-native birds representing three avian orders. Phylogenetic analysis of a 538 bp fragment of the gene encoding the virus 4b core polypeptide revealed two distinct variant clusters, with sequences from chickens (fowlpox) forming a third distinct basal cluster. Pox isolates from one of these two clusters appear closely related to canarypox and other passerine pox viruses, while the second appears more specific to Hawai'i. There was no evidence that birds were infected simultaneously with multiple pox virus variants based on evaluation of multiples clones from four individuals. No obvious temporal or geographic associations were observed and strict host specificity was not apparent among the 4b-defined field isolates. We amplified a 116 bp 4b core protein gene fragment from an 'Elepaio (Chasiempis sandwichensis) collected in 1900 on Hawai'i Island that clustered closely with the second of the two variants, suggesting that this variant has been in Hawai'i for at least 100 years. The high variation detected between the three 4b clusters provides evidence for multiple, likely independent introductions, and does not support the hypothesis of infection of native species through introduction of infected fowl. Preliminary experimental infections in native Hawai'i 'Amakihi (Hemignathus virens) suggest that the 4b-defined variants may be biologically distinct, with one variant appearing more virulent. These pox viruses may interact with avian malaria (Plasmodium relictum), another introduced pathogen in Hawaiian forest bird populations, through modulation of host immune responses. ?? 2007 Springer Science+Business Media B.V.

Conservation Genetics↗
USGS2021

Distilling professional opinion to gauge vulnerability of Guam avifauna to Brown Treesnake predation

The avifauna of Guam was devastated by the introduction of the Brown Treesnake, and the restoration of native birds would need to address the problem with eradication or suppression of BTS. With eradication of the snake unlikely in the near term, and suppression capabilities limited to specific finite areas, key information for reintroductions is how low BTS abundance will likely need to be for each bird species to be re-established based on their vulnerability to BTS predation. Here, we estimate vulnerability, which can no longer be measured directly, so biologists who are familiar with one or more of seven Guam birds were surveyed to obtain their knowledge and produce quantitative vulnerability estimates. As is typical of birds adapted to islands devoid of predators, respondents judged that our focal species exhibit few predator avoidance and tolerance traits, leaving body size as the prime determinant of vulnerability. Respondent opinion also holds that any behavior that reduces the likelihood of an encounter by BTS, e.g., roosting/nesting in palm crowns, cavity nesting, and in particular urban dwelling, substantially reduces vulnerability. Our results can help inform species-specific decisions about when it may be safe to consider the release of birds on Guam depending on the relative vulnerability of each species to predation by BTS.

Guam↗
USGS2024

Abundance of Long-billed Curlews on military lands in the Columbia Basin

Long-billed Curlews ( Numenius americanus ) are declining throughout North America, and the loss of grassland breeding habitat is one of the primary threats to the species. Intermountain West, in particular, has been identified as the most important region in North America for breeding curlews. Nevertheless, the density and abundance of Long-billed Curlews in this region is not well understood. Lands managed for military training can provide habitat for wildlife species of conservation concern, and increasingly these lands are becoming relevant to sustaining biodiversity. We conducted point count surveys of Long-billed Curlews on Department of Defense lands in the Columbia Basin near Boardman, Oregon, USA during two consecutive breeding seasons. We used multinomial-Poisson mixture models to estimate detection probability and density of curlews and to investigate environmental correlates of those metrics. Mean detection probability at a distance of 400 m was 0.45 and 0.61 in 2015 and 2016, respectively. In 2015, the clarity of skies increased detection probability, but in 2016, none of the variables we measured influenced detection probability. Mean predicted density was 3.3 (95% confidence interval: 2.4–4.7) and 1.8 (1.2–2.7) curlews/km² in 2015 and 2016, respectively. In both years, curlew density was higher in lower-elevation or topographically smoother areas. Estimated abundance of curlews in the study area was 639 (456–912) and 350 (237–520) birds in 2015 and 2016, respectively. The number of curlews appeared to fluctuate across the two years of our study, a demographic trend that may have been influenced by a wildfire in our study area in June 2015. The results of our study indicate that federal grasslands, including areas where military operations are conducted, can provide conservation benefit to breeding Long-billed Curlews.

Oregon↗
USGS2019

Changes in genetic diversity and differentiation in Red‐cockaded woodpeckers (Dryobates borealis) over the past century

Red‐cockaded woodpeckers (RCW; Dryobates borealis ) declined after human activities reduced their fire‐maintained pine ecosystem to <3% of its historical range in the southeastern United States and degraded remaining habitat. An estimated 1.6 million RCW cooperative breeding groups declined to about 3,500 groups with no more than 10,000 birds by 1978. Management has increased RCW population abundances since they were at their lowest in the 1990s. However, no range‐wide study has been undertaken since then to investigate the impacts of this massive bottleneck or infer the effects of conservation management and recent demographic recoveries. We used mitochondrial DNA sequences (mtDNA) and nine nuclear microsatellite loci to determine if range‐wide demographic declines resulted in changes to genetic structure and diversity in RCW by comparing samples collected before 1970 (mtDNA data only), between 1992 and 1995 (mtDNA and microsatellites), and between 2010 and 2014 (mtDNA and microsatellites). We show that genetic diversity has been lost as detected by a reduction in the number of mitochondrial haplotypes. This reduction was apparent in comparisons of pre‐1970 mtDNA data with data from the 1992–1995 and 2010–2014 time points, with no change between the latter two time points in mtDNA and microsatellite analyses. The mtDNA data also revealed increases in range‐wide genetic differentiation, with a genetically panmictic population present throughout the southeastern United States in the pre‐1970s data and subsequent development of genetic structure that has remained unchanged since the 1990s. Genetic structure was also uncovered with the microsatellite data, which like the mtDNA data showed little change between the 1992–1995 and 2010–2014 data sets. Temporal haplotype networks revealed a consistent, star‐like phylogeny, suggesting that despite the overall loss of haplotypes, no phylogenetically distinct mtDNA lineages were lost when the population declined. Our results may suggest that management during the last two decades has prevented additional losses of genetic diversity.

Alabama, Arkansas, Florida, Georgia, Kentucky, Lou↗
USGS2026

Activity, but not size of Black-tailed Praire Dog colonies, is associated with higher Athene cunicularia hypugaea (Western Burrowing Owl) occupancy and reproductive success in the shortgrass prairie

Conservation in fragmented ecosystems, such as grasslands, has historically put more value on larger habitat patches but recent research suggests that small, high-quality habitat patches hold important conservation value. In many grassland systems, Athene cunicularia hypugaea (Western Burrowing Owl) relies on habitat patches created by Cynomys ludovicianus (Black-tailed Prairie Dog; hereafter prairie dog). Prairie dogs create important nesting habitat for A. c. hypugaea and other grassland birds. We examined the effect of size and characteristics of prairie dog colonies on A. c. hypugaea occupancy and reproductive success. We specifically looked at how colony size, prairie dog activity level, and vegetation characteristics influence these population parameters on 175 survey plots throughout eastern Colorado, U.S., across two sample years. Results are based on detections of adult and owlet A. c. hypugaea collected by paired observers traversing transects through study plots during the 2022 and 2023 A. c. hypugaea nesting seasons (May–August). Our top multistate occupancy model indicated that latitude affects A. c. hypugaea occupancy probabilities. Occupancy was higher in southern Colorado compared to northern Colorado. In addition, prairie dog activity was positively associated with A. c. hypugaea reproductive success. Colony size and vegetation characteristics were generally uninformative predictors of A. c. hypugaea occupancy and reproductive success. We compared our results to a previous A. c. hypugaea population assessment conducted within our study area in 2005 and found that active prairie dog colonies positively affected A. c. hypugaea local colonization while local extinction was driven by a transition of active prairie dog colonies to inactive. This study highlights the importance of high-quality prairie dog habitat patches for A. c. hypugaea nesting in fragmented grassland ecosystems, regardless of patch size.

Colorado↗
USGS2004

Distribution and abundance of the Mariana subspecies of the Common Moorhen

Island-wide surveys for the endangered Mariana subspecies of the Common Moorhen ( Gallinula chloropus guami ) were conducted on Guam and the Commonwealth of the Northern Mariana Islands from May through September 2001. Based on these counts, the total adult moorhen population is estimated to be 287, with 154, 41, 2, and 90 adult moorhens on Saipan, Tinian, Rota, and Guam, respectively. Results suggest an overall increase in birds on Saipan and Tinian, although moorhen numbers on Guam may be declining. High counts of moorhens on Lake Hagoi, Tinian, during the wet season suggested movement from Saipan to Tinian occurs at the onset of the wet season each year. Conservation efforts need to consider Saipan and Tinian moorhens as a single demographic unit. Further, monitoring of moorhens, invasive vegetation management, and predator and ungulate control on wetlands are critical for this small population.

Waterbirds↗
USGS2007

Natal location influences movement and survival of a spatially structured population of snail kites

Despite the accepted importance of the need to better understand how natal location affects movement decisions and survival of animals, robust estimates of movement and survival in relation to the natal location are lacking. Our study focuses on movement and survival related to the natal location of snail kites in Florida and shows that kites, in addition to exhibiting a high level of site tenacity to breeding regions, also exhibit particular attraction to their natal region. More specifically, we found that estimates of movement from post-dispersal regions were greater toward natal regions than toward non-natal regions (differences were significant for three of four regions). We also found that estimates of natal philopatry were greater than estimates of philopatry to non-natal regions (differences were statistically significant for two of four regions). A previous study indicated an effect of natal region on juvenile survival; in this study, we show an effect of natal region on adult survival. Estimates of adult survival varied among kites that were hatched in different regions. Adults experienced mortality rates characteristic of the region occupied at the time when survival was measured, but because there is a greater probability that kites will return to their natal region than to any other regions, their survival was ultimately influenced by their natal region. In most years, kites hatched in southern regions had greater survival probabilities than did kites hatched in northern regions. However, during a multiregional drought, one of the northern regions served as a refuge from drought, and during this perturbation, survival was greater for birds hatched in the north. Our study shows that natal location may be important in influencing the ecological dynamics of kites but also highlights the importance of considering temporal variation in habitat conditions of spatially structured systems when attempting to evaluate the conservation value of habitats.

Oecologia↗
USGS2008

Importance of agricultural landscapes to nesting burrowing owls in the Northern Great Plains, USA

Anthropogenic habitat loss and fragmentation are the principle factors causing declines of grassland birds. Declines in burrowing owl (Athene cunicularia) populations have been extensive and have been linked to habitat loss, primarily the decline of black-tailed prairie dog (Cynomys ludovicianus) colonies. Development of habitat use models is a research priority and will aid conservation of owls inhabiting human-altered landscapes. From 2001 to 2004 we located 160 burrowing owl nests on prairie dog colonies on the Little Missouri National Grassland in North Dakota. We used multiple linear regression and Akaike's Information Criterion to estimate the relationship between cover type characteristics surrounding prairie dog colonies and (1) number of owl pairs per colony and (2) reproductive success. Models were developed for two spatial scales, within 600 m and 2,000 m radii of nests for cropland, crested wheatgrass (Agropyron cristatum), grassland, and prairie dog colonies. We also included number of patches as a metric of landscape fragmentation. Annually, fewer than 30% of prairie dog colonies were occupied by owls. None of the models at the 600 m scale explained variation in number of owl pairs or reproductive success. However, models at the 2,000 m scale did explain number of owl pairs and reproductive success. Models included cropland, crested wheatgrass, and prairie dog colonies. Grasslands were not included in any of the models and had low importance values, although percentage grassland surrounding colonies was high. Management that protects prairie dog colonies bordering cropland and crested wheatgrass should be implemented to maintain nesting habitat of burrowing owls. ?? 2008 Springer Science+Business Media B.V.

Landscape Ecology↗
USGS2021

A systematic review of potential habitat suitability for the jaguar Panthera onca in central Arizona and New Mexico, USA

In April 2019, the U.S. Fish and Wildlife Service (USFWS) released its recovery plan for the jaguar Panthera onca after several decades of discussion, litigation and controversy about the status of the species in the USA. The USFWS estimated that potential habitat, south of the Interstate-10 highway in Arizona and New Mexico, had a carrying capacity of c. six jaguars, and so focused its recovery programme on areas south of the USA–Mexico border. Here we present a systematic review of the modelling and assessment efforts over the last 25 years, with a focus on areas north of Interstate-10 in Arizona and New Mexico, outside the recovery unit considered by the USFWS. Despite differences in data inputs, methods, and analytical extent, the nine previous studies found support for potential suitable jaguar habitat in the central mountain ranges of Arizona and New Mexico. Applying slightly modified versions of the USFWS model and recalculating an Arizona-focused model over both states provided additional confirmation. Extending the area of consideration also substantially raised the carrying capacity of habitats in Arizona and New Mexico, from six to 90 or 151 adult jaguars, using the modified USFWS models. This review demonstrates the crucial ways in which choosing the extent of analysis influences the conclusions of a conservation plan. More importantly, it opens a new opportunity for jaguar conservation in North America that could help address threats from habitat losses, climate change and border infrastructure.

Arizona, New Mexico↗
USGS2019

Trends in landbird density at two national parks in fragmented, mixed-use landscapes of the Pacific Northwest

National parks play a key role in conserving species by providing landscapes where threats from anthropogenic disturbance are reduced. In a recent study of 3 large wilderness parks in the Pacific Northwest, nearly all landbird species were found to be stable or increasing. Nonetheless, contemporary results from the Breeding Bird Survey and mark-recapture studies fuel concerns that some landbirds in the Pacific Northwest are trending in sync with many North America species in widespread decline. Although landbird populations might be thriving in large parks with extensive old-growth forest, those in smaller parks with less intact wilderness and higher ratios of edge-to-interior habitat might reflect the stressors inherent in more human-dominated landscapes. We conducted landbird point-count surveys from 2005 to 2016 in 2 national historical parks situated in the more human-dominated landscapes of this region, San Juan Island National Historical Park and Lewis and Clark National Historical Park. Established primarily to protect cultural resources, these parks lack old-growth forest and consist of relatively small parcels embedded in fragmented, multi-use landscapes. Here, we apply recent developments in point-count analysis to estimate trends in population density for 50 landbird species commonly detected in these small parks, including lagged effects of precipitation and temperature on the annual density of each species, and effects of survey conditions on species detection. All but 3 species exhibited stable densities in both parks, and more than half of the populations analyzed clearly increased in density over the study period. Notable exceptions were single-park declines in Olive-sided Flycatcher ( Contopus cooperi ), Northern Flicker ( Colaptes anratus ), and Hutton's Vireo ( Vireo huttoni ). Annual variation in population density was often related to climate, with generally positive responses to a recent deficit in annual precipitation-as-snow, and more variable responses to higher mean spring temperature. These results reinforce trends estimated for 3 large national parks in the Pacific Northwest, suggesting recent stability of landbird populations in parks of this region, independent of park size or setting.

Northwestern Naturalist↗