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USGS2014

Evaluating coastal landscape response to sea-level rise in the northeastern United States: approach and methods

The U.S. Geological Survey is examining effects of future sea-level rise on the coastal landscape from Maine to Virginia by producing spatially explicit, probabilistic predictions using sea-level projections, vertical land movement rates (due to isostacy), elevation data, and land-cover data. Sea-level-rise scenarios used as model inputs are generated by using multiple sources of information, including Coupled Model Intercomparison Project Phase 5 models following representative concentration pathways 4.5 and 8.5 in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A Bayesian network is used to develop a predictive coastal response model that integrates the sea-level, elevation, and land-cover data with assigned probabilities that account for interactions with coastal geomorphology as well as the corresponding ecological and societal systems it supports. The effects of sea-level rise are presented as (1) level of landscape submergence and (2) coastal response type characterized as either static (that is, inundation) or dynamic (that is, landform or landscape change). Results are produced at a spatial scale of 30 meters for four decades (the 2020s, 2030s, 2050s, and 2080s). The probabilistic predictions can be applied to landscape management decisions based on sea-level-rise effects as well as on assessments of the prediction uncertainty and need for improved data or fundamental understanding. This report describes the methods used to produce predictions, including information on input datasets; the modeling approach; model outputs; data-quality-control procedures; and information on how to access the data and metadata online.

Open-File Report↗

USGS2011

Ruddy Shelduck Tadorna ferruginea home range and habitat use during the non-breeding season in Assam, India

India is an important non-breeding ground for migratory waterfowl in the Central Asian Flyway. Millions of birds visit wetlands across the country, yet information on their distribution, abundance, and use of resources is rudimentary at best. Limited information suggests that populations of several species of migratory ducks are declining due to encroachment of wetland habitats largely by agriculture and industry. The development of conservation strategies is stymied by a lack of ecological information on these species. We conducted a preliminary assessment of the home range and habitat use of Ruddy Shelduck Tadorna ferruginea in the northeast Indian state of Assam. Seven Ruddy Shelducks were fitted with solar-powered Global Positioning System (GPS) satellite transmitters, and were tracked on a daily basis during the winter of 2009-2010. Locations from all seven were used to describe habitat use, while locations from four were used to quantify their home range, as the other three had too few locations (< 30) for home range estimation. A Brownian Bridge Movement Model (BBMM), used to estimate home ranges, found that the Ruddy Shelduck had an average core use area (i.e. the contour defining 50% of positions) of 40 km 2 (range = 22-87 km 2 ) and an average home range (95% contour) of 610 km 2 (range = 222-1,550 km 2 ). Resource Selection Functions (RSF), used to describe habitat use, showed that the birds frequented riverine wetlands more than expected, occurred on grasslands and shrublands in proportion to their availability, and avoided woods and cropland habitats. The core use areas for three individuals (75%) were on the Brahmaputra River, indicating their preference for riverine habitats. Management and protection of riverine habitats and nearby grasslands may benefit conservation efforts for the Ruddy Shelduck and waterfowl species that share these habitats during the non-breeding season.

Assam↗

USGS1988

Assessment of the role of bottomland hardwoods in sediment and erosion control

Drainage and clearing of bottomland hardwoods have long been recognized by the U.S. Environmental Protection Agency (EPA) and the U.S. Fish and Wildlife Service (Service) as important impacts of Federal water projects in the lower Mississippi River Valley. More recently, the water quality impacts of such projects (e.g., increases in sediments, nutrients, and pesticides) have also become of concern. In 1984, in an effort to better define problems concerning wetland losses and water degradation, EPA initiated a cooperative project with the Western Energy and Land Use Team (now the National Ecology Research Center) of the Service. Three phases of the project were identified: 1. To collect existing literature and data; 2. To select, develop, and test the utility of methods to quantify the relationships between land use, cover types, soils, hydrology, and water quality (as represented by sediment); and 3. To apply selected methodologies to several sites within the Yazoo Basin of Mississippi to determine the, potential effectiveness of various management alternatives to reduce sediment yield, increase sediment deposition, and improve water quality. Methods development focused on linking a simulation of water and sediment movement to a computerized geographic information system. We had several objectives for the resulting model. We desired that it should: 1. Estimate the importance of bottomland and hardwoods as a cover type that performs the functions of erosion and sediment control, 2. Simulate effects of proportions of ' various cover types and their specific spatial configurations, 3. Be applicable to moderately large spatial areas with minimal site-specific calibration, 4. Simulate spatial patterns of sediment loss-gain over time, and 5. Represent both sediment detachment and transport. While it was recognized that impacts and management alternatives could be sorted roughly into landscape measures and channel measures, the decision was made to focus study efforts mainly on landscape measures. Landscape measures include altered drainage and flooding patterns, altered cover types (e.g., conversion of bottomland hardwoods to agricultural crops, reforestation of cropland to bottomland hardwoods, and creation of riparian buffer strips), altered cropping and tillage patterns, altered routing of water, and creation of buffer strips along wetlands and channel margins. Channel measures include vegetative bank stabilization, grade control structures, and regulation of channel water volume and velocity. During the first year of the study, EPA decided not to fund the third phase of the project. This required considerable rescoping of the project with the result that application of the sediment mobilization, routing, and deposition models to various management alternatives and portions of the Yazoo Basin was somewhat restricted. We believe, however, that this report will provide a good understanding of the various modes of sediment mobilization, transport, and deposition within the Yazoo Basin, as well as of the role of bottomland hardwoods. The model developed in this study could be applied to a variety of management or mitigation alternatives prior to implementation to determine their relative effectiveness. Policy, political, and socio-economic consequences of any proposed management/mitigation practice, however, must ultimately be taken into consideration by those charged with management of water resources within the Yazoo Basin before any practice is implemented. This study makes no effort to judge the feasibility of management alternatives in this regard.

Report↗

USGS2010

Modeling amphibian energetics, habitat suitability, and movements of western toads, Anaxyrus (=Bufo) boreas, across present and future landscapes

Effective conservation of amphibian populations requires the prediction of how amphibians use and move through a landscape. Amphibians are closely coupled to their physical environment. Thus an approach that uses the physiological attributes of amphibians, together with knowledge of their natural history, should be helpful. We used Niche Mapper™ to model the known movements and habitat use patterns of a population of Western toads ( Anaxyrus (= Bufo ) boreas ) occupying forested habitats in southeastern Idaho. Niche Mapper uses first principles of environmental biophysics to combine features of topography, climate, land cover, and animal features to model microclimates and animal physiology and behavior across landscapes. Niche Mapper reproduced core body temperatures ( T c ) and evaporation rates of live toads with average errors of 1.6 ± 0.4 °C and 0.8 ± 0.2 g/h, respectively. For four different habitat types, it reproduced similar mid-summer daily temperature patterns as those measured in the field and calculated evaporation rates (g/h) with an average error rate of 7.2 ± 5.5%. Sensitivity analyses indicate these errors do not significantly affect estimates of food consumption or activity. Using Niche Mapper we predicted the daily habitats used by free-ranging toads; our accuracy for female toads was greater than for male toads (74.2 ± 6.8% and 53.6 ± 15.8%, respectively), reflecting the stronger patterns of habitat selection among females. Using these changing to construct a cost surface, we also reconstructed movement paths that were consistent with field observations. The effect of climate warming on toads depends on the interaction of temperature and atmospheric moisture. If climate change occurs as predicted, results from Niche Mapper suggests that climate warming will increase the physiological cost of landscapes thereby limiting the activity for toads in different habitats.

Idaho↗

USGS2023

Seasonal shifts in diel vertical migrations by lake-dwelling coastal cutthroat trout, Oncorhynchus clarkii clarkii, reflect thermal regimes and prey distributions

Lakes provide important habitat for salmonids that may use them as a primary feeding area between periods of reproduction. The seasonal changes in vertical thermal structure in lakes can affect the distribution of salmonids on seasonal and diel time scales as they search for, consume, and digest prey that also exploits the water column's distribution of food, temperature and light. Our goal was to analyse the vertical distribution of wild, native coastal cutthroat trout ( Oncorhynchus clarkii clarkii ) in Lake Washington on daily and seasonal time scales. This lake is stratified in the summer and isothermal in winter, allowing us to compare vertical movements between periods with and without thermal structure in water 50 m deep. We predicted that trout would be deeper in the water column during stratified months and shallower during isothermal months, and shallower at night than in the day. Overall, the trout showed these patterns in the depths and temperatures they occupied, tending to be within or below the thermocline in the summer but not in the coolest water available, and closer to the surface when the lake was isothermal. The trout were also closer to the surface at night and deeper during the day. The vertical range of these diel movements shifted with the seasons–deepest in October, as the thermocline deepened and weakened, and shallowest in January when the lake was isothermal. These seasonal and diel vertical distribution patterns by the trout optimise metabolism for growth, and facilitate feeding on planktivorous fishes that also show seasonal and diel vertical distribution changes.

Washington↗

USGS1966

Insecticide contaminations in wetland habitats and their effects on fish- eating birds

An unusual mortality of fish-eating birds occurred at the Tule Lake National Wildlife Refuge in California between 1960 and 1962. Over 1100 dead birds of ten species were found during that period. Investigations of the mortality indicated that birds died as a result of their exposure to toxaphene, which was applied to adjoining agricultural areas, transported to the refuge in waste irrigation water, and accumulated in fish eaten by the birds. Toxaphene was used in agriculture for only 3 years, 1958-60, and by 1962 residues were no longer found in the marsh habitat. However, results also showed that a potentially hazardous contamination of DDT and its metabolites was present in the birds and the environment. Studies were, therefore, continued to determine the food-chain relationships of DDT in marsh ecosystems, and the effects of the insecticide on birds. Sampling for insecticide residues was undertaken at four waterfowl refuges, each representing a somewhat different set of environmental conditions. DDT residues in water at each refuge were found to be relatively low, but filtered samples showed that residues in suspended material were 10 000 to 20 000 times as great as those in the filtrate. Much of the suspended material was organic matter, which is an important source of energy for the ecosystems. In environments with invertebrates, DDT residues were relatively low in sediments and high in fish, while residues in vegetation were highest where invertebrates were absent. Results suggest that organic materials and invertebrates can be important factors in determining the fate and involvement of insecticides in aquatic environments. Studies of the movements, exposure to pesticides, productivity, and longevity of individuals in three nesting colonies of White Pelicans were begun in 1962 to depict the relationships of pesticides to a migratory population of birds dependent upon wetland habitats. To date there is no evidence that the exposure of pelicans to DDT is influencing the population dynamics of the birds.

California, Oregon↗

USGS2023

Conservation at the nexus of niches: Multidimensional niche modeling to improve management of Prairie Chub

Objective A central challenge in applied ecology is understanding how organisms are spatially and temporally distributed and how management might be tailored to maintain or restore species distributions. The niche concept is central to understanding species distributions, but the diversity of niche definitions requires that multiple dimensions be considered. For example, the Grinnellian niche concept focuses on environmental conditions that allow species to persist, the Eltonian niche concept stresses the influence of biotic interactions, and the fundamental niche concept considers both abiotic and biotic environmental features to define spaces that organisms could occupy. Methods We combined abiotic ( A ), biotic ( B ), and movement ( M ) information (collectively, BAM model) to map the multidimensional niche of Prairie Chub Macrhybopsis australis , a regionally endemic freshwater fish currently under review for listing under the Endangered Species Act. We estimated A using remotely sensed environmental riverscape variables, B using the spatial distribution of a hybridization zone between Prairie Chub and Shoal Chub M. hyostoma , and M using data from a mark–recapture study. Result The BAM model estimated the spatial extent of multiple niches, including the Grinnellian ( A ; extent = 944 km of river), Eltonian ( B ; 2974 km), and fundamental niche (overlap of A + B ; 645 km) niches. When A , B , and M components were combined, the estimated extent of the Prairie Chub niche was 645 km. Conclusion Our work shows that the realized, multidimensional niche of Prairie Chub includes medium to large rivers with high habitat connectivity in the upper–middle Red River basin upstream of the distribution of Shoal Chub. The current Prairie Chub distribution could be maintained by preventing further habitat fragmentation and maintaining the environmental gradient separating Prairie Chub from Shoal Chub. Expansion of the species distribution may be possible through restoration of longitudinal fluvial connectivity.

North American Journal of Fisheries Management↗

USGS2006

Gila monster (Heloderma suspectum)

Like the saguaro cactus (Carnegia gigantea) and the rattlesnake, the Gila monster is emblematic of the desert Southwest. The Gila monster is not only the largest lizard native to the United States, but also one of only two known species of venomous lizard in the Americas. This stout-bodied lizard can grow to 50 cm (20 in) and is covered with black and pink or orange markings and bead-like scales. The Gila monster's range is centered in western and southern Arizona, continuing south to Sonora, Mexico. Despite public fascination with the species, relatively little is known about the ecology and behavior of the Gila monster in the wild. For this reason, managers at Tonto National Monument, Arizona, contacted the U.S. Geological Survey (USGS) to investigate why Gila monsters were being seen in developed areas of the park, particularly crossing the main road. Managers were concerned about possible lizard-human conflicts and the risk of vehicle traffic killing Gila monsters. USGS scientists initiated a research effort in Tonto National Monument beginning in 2004 to provide information needed to make management decisions and improve scientific understanding of the species. Specifically, USGS scientists examined the movement patterns, range requirements, dietary habits, and use of developed areas by Gila monsters within the park. The 2004 research effort also extended a program begun in Tonto National Monument in 1994 to recognize individual Gila monsters based on unique dorsal patterns identified from photographs.

Fact Sheet↗

USGS2002

Test for age-specificity in survival of the common tern

Much effort in life-history theory has been addressed to the dependence of life-history traits on age, especially the phenomenon of senescence and its evolution. Although senescent declines in survival are well documented in humans and in domestic and laboratory animals, evidence for their occurrence and importance in wild animal species remains limited and equivocal. Several recent papers have suggested that methodological issues may contribute to this problem, and have encouraged investigators to improve sampling designs and to analyse their data using recently developed approaches to modelling of capture-mark-recapture data. Here we report on a three-year, two-site, mark-recapture study of known-aged common terns (Sterna hirundo) in the north-eastern USA. The study was nested within a long-term ecological study in which large numbers of chicks had been banded in each year for > 25 years. We used a range of models to test the hypothesis of an influence of age on survival probability. We also tested for a possible influence of sex on survival. The cross-sectional design of the study (one year's parameter estimates) avoided the possible confounding of effects of age and time. The study was conducted at a time when one of the study sites was being colonized and numbers were increasing rapidly. We detected two-way movements between the sites and estimated movement probabilities in the year for which they could be modelled. We also obtained limited data on emigration from our study area to more distant sites. We found no evidence that survival depended on either sex or age, except that survival was lower among the youngest birds (ages 2-3 years). Despite the large number of birds included in the study (1599 known-aged birds, 2367 total), confidence limits on estimates of survival probability were wide, especially for the oldest age-classes, so that a slight decline in survival late in life could not have been detected. In addition, the cross-sectional design of this study meant that a decline in survival probability within individuals (actuarial senescence) could have been masked by heterogeneity in survival probability among individuals (mortality selection). This emphasizes the need for the development of modelling tools permitting separation of these two phenomena, valid under field conditions in which the recapture probabilities are less than one.

Book chapter↗

USGS2024

Evaluating ecosystem protection and fragmentation of the world's major mountain regions

Conserving mountains is important for protecting biodiversity because they have high beta diversity and endemicity, facilitate species movement, and provide numerous ecosystem benefits for people. Mountains are often thought to have lower levels of human modification and contain more protected area than surrounding lowlands. To examine this, we compared biogeographic attributes of the largest, contiguous, mountainous region on each continent. In each region, we generated detailed ecosystems based on Köppen−Geiger climate regions, ecoregions, and detailed landforms. We quantified anthropogenic fragmentation of these ecosystems based on human modification classes of large wild areas, shared lands, and cities and farms. Human modification for half the mountainous regions approached the global average, and fragmentation reduced the ecological integrity of mountain ecosystems up to 40%. Only one-third of the major mountainous regions currently meet the Kunming-Montreal Global Biodiversity Framework target of 30% coverage for all protected areas; furthermore, the vast majority of ecosystem types present in mountains were underrepresented in protected areas. By measuring ecological integrity and human-caused fragmentation with a detailed representation of mountain ecosystems, our approach facilitates tracking progress toward achieving conservation goals and better informs mountain conservation.

Conservation Biology↗

USGS2005

Landscape structure and plague occurrence in black-tailed prairie dogs on grasslands of the western USA

Landscape structure influences the abundance and distribution of many species, including pathogens that cause infectious diseases. Black-tailed prairie dogs in the western USA have declined precipitously over the past 100 years, most recently due to grassland conversion and their susceptibility to sylvatic plague. We assembled and analyzed two long-term data sets on plague occurrence in black-tailed prairie dogs to explore the hypotheses that plague occurrence is associated with colony characteristics and landscape context. Our two study areas (Boulder County, Colorado, and Phillips County, Montana) differed markedly in degree of urbanization and other landscape characteristics. In both study areas, we found associations between plague occurrence and landscape and colony characteristics such as the amount of roads, streams and lakes surrounding a prairie dog colony, the area covered by the colony and its neighbors, and the distance to the nearest plague-positive colony. Logistic regression models were similar between the two study areas, with the best models predicting positive effects of proximity to plague-positive colonies and negative effects of road, stream and lake cover on plague occurrence. Taken together, these results suggest that roads, streams and lakes may serve as barriers to plague in black-tailed prairie dog colonies by affecting movement of or habitat quality for plague hosts or for fleas that serve as vectors for the pathogen. The similarity in plague correlates between urban and rural study areas suggests that the correlates of plague are not altered by uniquely urban stressors. ?? Springer 2005.

Landscape Ecology↗

USGS2014

Bird migration and avian influenza: a comparison of hydrogen stable isotopes and satellite tracking methods

Satellite-based tracking of migratory waterfowl is an important tool for understanding the potential role of wild birds in the long-distance transmission of highly pathogenic avian influenza. However, employing this technique on a continental scale is prohibitively expensive. This study explores the utility of stable isotope ratios in feathers in examining both the distances traveled by migratory birds and variation in migration behavior. We compared the satellite-derived movement data of 22 ducks from 8 species captured at wintering areas in Bangladesh, Turkey, and Hong Kong with deuterium ratios (δD) in the feathers of these and other individuals captured at the same locations. We derived likely molting locations from the satellite tracking data and generated expected isotope ratios based on an interpolated map of δD in rainwater. Although δD was correlated with the distance between wintering and molting locations, surprisingly, measured δD values were not correlated with either expected values or latitudes of molting sites. However, population-level parameters derived from the satellite-tracking data, such as mean distance between wintering and molting locations and variation in migration distance, were reflected by means and variation of the stable isotope values. Our findings call into question the relevance of the rainfall isotope map for Asia for linking feather isotopes to molting locations, and underscore the need for extensive ground truthing in the form of feather-based isoscapes. Nevertheless, stable isotopes from feathers could inform disease models by characterizing the degree to which regional breeding populations interact at common wintering locations. Feather isotopes also could aid in surveying wintering locations to determine where high-resolution tracking techniques (e.g. satellite tracking) could most effectively be employed. Moreover, intrinsic markers such as stable isotopes offer the only means of inferring movement information from birds that have died as a result of infection. In the absence of feather based-isoscapes, we recommend a combination of isotope analysis and satellite-tracking as the best means of generating aggregate movement data for informing disease models.

Ecological Indicators↗

USGS2009

A hierarchical model for estimating density in camera-trap studies

Estimating animal density using capture–recapture data from arrays of detection devices such as camera traps has been problematic due to the movement of individuals and heterogeneity in capture probability among them induced by differential exposure to trapping. We develop a spatial capture–recapture model for estimating density from camera-trapping data which contains explicit models for the spatial point process governing the distribution of individuals and their exposure to and detection by traps. We adopt a Bayesian approach to analysis of the hierarchical model using the technique of data augmentation. The model is applied to photographic capture–recapture data on tigers Panthera tigris in Nagarahole reserve, India. Using this model, we estimate the density of tigers to be 14·3 animals per 100 km 2 during 2004. Synthesis and applications. Our modelling framework largely overcomes several weaknesses in conventional approaches to the estimation of animal density from trap arrays. It effectively deals with key problems such as individual heterogeneity in capture probabilities, movement of traps, presence of potential ‘holes’ in the array and ad hoc estimation of sample area. The formulation, thus, greatly enhances flexibility in the conduct of field surveys as well as in the analysis of data, from studies that may involve physical, photographic or DNA-based ‘captures’ of individual animals.

Journal of Applied Ecology↗

USGS1997

Recovery strategies for the California clapper rail (Rallus longirostris obsoletus) in the heavily-urbanized San Francisco estuarine ecosystem

The California clapper rail ( Rallus longirostris obsoletus ), a Federal- and State-listed endangered marsh bird, has a geographic range restricted to one of the most heavily-urbanized estuaries in the world. The rail population has long been in a state of decline, although the exact contribution of each of the many contributing causes remains unclear. The rail is one of the key targets of emerging plans to conserve and restore tidal marshlands. Reduction of tidal marsh habitat, estimated at 85–95%, has been the major historical cause of rail decline. Increased predation intensity may be the more important present problem, because habitat fragmentation and alteration coupled with the invasion of the red fox have made the remaining populations more vulnerable to predators. Population viability analysis shows that adult survivorship is the key demographic variable; reversals in population fate occur over a narrow range of ecologically realistic values. Analysis of habitat requirements and population dynamics of the clapper rail in the San Francisco Estuary shows that decreased within-marsh habitat quality, particularly reduction of tidal flows and alteration of drainage, is an important barrier to population recovery. Management and restoration activities should emphasize the development of well-channelized high tidal marsh, because this is the key requirement of rail habitat. Developing effective restoration programs depends upon having information that field research will not provide. The effect of spatial pattern of reserves requires accurate estimation of the effects of prédation and inter-marsh movement, both of which are practically impossible to measure adequately. It will be necessary to develop and use simulation models that can be applied to geographic data to accomplish this task.

Landscape and Urban Planning↗

USGS2025

Landscape changes elevate the risk of avian influenza virus diversification and emergence in the East Asian–Australasian Flyway

Highly pathogenic avian influenza viruses (HPAIV) persistently threaten wild waterfowl, domestic poultry, and public health. The East Asian–Australasian Flyway plays a crucial role in HPAIV dynamics due to its large populations of migratory waterfowl and poultry. Over recent decades, this flyway has undergone substantial landscape changes, including both losses and gains of waterfowl habitats. These changes can affect waterfowl distributions, increase contact with poultry, and consequently alter ecological conditions that favor avian influenza virus (AIV) evolution. However, limited research has assessed these likely impacts. Here, we integrated empirical data and an individual-based model to simulate AIV transmission in migratory waterfowl and domestic poultry, including wild-to-poultry spillover and reassortment dynamics in poultry, across landscapes representing the years 2000 and 2015. We used the reassortment incidence as a proxy for ecological and transmission conditions that support viral diversification and the emergence of novel subtypes. Our simulations show that landscape change reshaped the waterfowl distribution, facilitated bird aggregation at improved habitats, increased coinfection, and raised reassortment rate by 1,593%, indicating a substantially higher potential for viral diversification and emergence. Model-generated risk maps show expanded and increased reassortment risk in southeastern China, the Yellow River Basin, and northeastern China. These findings suggest the importance of landscape change as a driver of potential AIV diversification and subtype emergence. This underscores the need for interdisciplinary approaches that integrate landscape dynamics, host movement, and viral evolution to better assess and mitigate future risk.

East Asian–Australasian Flyway↗

USGS2014

Post-independence fledgling ecology in a migratory songbird: Implications for breeding-grounds conservation

For migratory songbirds, breeding-grounds conservation and management plans are generally focused on habitat associated with locations of singing males and sometimes nesting females. However, habitat structure is often different in areas used for raising fledglings compared with areas used for song territories, and very little is known about habitat use by fledglings after independence from adult care. From 2010 to 2012, we used radiotelemetry to monitor 68 fledgling golden-winged warblers V ermivora chrysoptera after independence from adult care in mixed managed forests of Minnesota, US and Manitoba, Canada. This species is of high conservation concern in the US, is listed as threatened in Canada and is listed as near threatened on the International Union for Conservation of Nature Red List. We assessed distance and orientation of independent fledgling movements and we used compositional analysis to test for selection among cover types. Fledglings of this species, commonly described as a shrubland specialist, selected mature forest (78% of locations) over all other cover types, and foraged in forest canopy and understory in mixed-species flocks. Fledgling golden-winged warbler movements were apparently associated with habitat optimization (although prioritizing foraging over predator avoidance), and likely not with commencement of migration, or scouting future breeding territories. Ten days after independence, fledglings were an average of 1238 m north of their nest, which may be related to homing-target formation and the species' northward range expansion. We conclude that consideration for independent fledgling habitat associations is necessary for developing full-fledged forest management plans on the breeding grounds of migratory songbirds.

Manitoba, Minnesota↗

USGS2022

Migration Mapper: Identifying movement corridors and seasonal ranges for large mammal conservation

Modern tracking technology has facilitated a novel understanding of terrestrial mammal movement while revealing that movements are being truncated and lost. The first step towards conserving mobile animals is identifying movement corridors and key seasonal ranges. Yet, the identification and subsequent mapping of these important areas has remained a challenge due to the analytical skills necessary to conduct such analyses. Migration Mapper (MM) is a user-friendly software that provides tools to analyse global positioning system (GPS) collar data to create season-specific, population-level polygons representing areas where most of a population moves (i.e. movement corridors) and areas where most of a population spends time (e.g. high-use areas, seasonal ranges). MM consists of six standalone modules including data cleaning and review, seasonal movement delineation, movement model application, calculation of population-level outputs and visualization of results. Analysis of GPS data using MM can provide the spatial polygons necessary to facilitate conservation and policy planning. New initiatives at the local and global levels are already beginning to use MM to facilitate conservation of large, terrestrial mammals.

Methods in Ecology and Evolution↗

USGS2015

The cost of reproduction: differential resource specialization in female and male California sea otters

Intraspecific variation in behavior and diet can have important consequences for population and ecosystem dynamics. Here, we examine how differences in reproductive investment and spatial ecology influence individual diet specialization in male and female southern sea otters ( Enhydra lutris nereis ). We hypothesize that greater reproductive constraints and smaller home ranges of females lead to more pronounced intraspecific competition and increased specialization. We integrate stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope analysis of sea otter vibrissae with long-term observational studies of five subpopulations in California. We define individual diet specialization as low ratios of within-individual variation (WIC) to total population niche width (TNW). We compare isotopic and observational based metrics of WIC/TNW for males and females to data on population densities, and movement patterns using both general linear and linear mixed-effects models. Consistent with our hypothesis, increasing population density is associated with increased individual diet specialization by females but not by males. Additionally, we find the amount of coastline in a sea otter’s home range positively related with individual dietary variability, with increased range span resulting in weaker specialization for both males and females. We attribute our results to sex-based differences in movement, with females needing to specialize in their small ranges to maximize energy gain, and posit that the paradigm of individual prey specialization in sea otters with increased intraspecific competition may be a pattern driven largely by females. Our work highlights a potentially broader role of sex in the mechanistic pressures promoting and maintaining diet specialization.

California↗