Despite the ecological expression and conservation importance of diverse behavioral tactics in animals, there is often friction associated with conventional analytical approaches and inference concerning variation in spatial behavior. Implicitly or explicitly, population-level inferences are often the main objective of studies, but interpretations can be ambiguous in the presence of divergent behavioral tactics across individuals or cohorts, as with generalist species. We pursued a novel analytical approach and assessed the underlying mechanisms driving variation in spatial behaviors of generalist species using the American black bear (Ursus americanus) as our focal species. We quantified individual variation in habitat selection expressed by black bears using individual models for 35-collared bears across four study areas in Wyoming, USA. We modeled how state-dependent factors (age, sex, δ15Nitrogen and body fat) and resource availability influenced behavioral variation in resource selection. We observed vast variation among individuals, demonstrating patterns consistent with a generalist species. Black bear resource selection differed with changes in state-dependence and resource availability. Specifically, traits uniquely important to black bear success, body fat and carnivory, explained variation in selection for forage indexed by NDVI, forests, and riparian areas. Environmental heterogeneity via differences in resource availability magnified behavioral variation in resource selection by black bears. Selection trends for NDVI and deciduous shrubs were explained by resource availability, indicating black bears exhibited functional responses in habitat selection. These insights emerged from our analytical approach; had we implemented a more conventional, population-level assessment we would have simply concluded that black bears displayed behavioral neutrality with respect to forage resources. Acknowledgement of behavioral variation when considering spatial behavior of generalist species provides a more representative understanding of individuals within a population, and our analytical approach offers a solution to uncovering drivers of individual variation in spatial behavior.

The current framework for understanding large-scale animal movement strategies (i.e., migration, nomadism, or residency) suggests that each strategy is associated with specific combinations of resource spatial heterogeneity and temporal predictability. While there is support for this framework across ecosystems, modern tracking data has revealed that all three strategies can occur in a single population. Using 21 years of GPS data from seven populations (n = 239) of pronghorn (Antilocapra americana) and twelve populations (n = 283) of elk (Cervus canadensis) across Wyoming, USA, we examined the support for resource-based hypotheses in predicting the occurrence of migrants, nomads, and residents. Using model selection, we found support for the hypothesis that greater spatial homogeneity and less temporal predictability are associated with residency, and vice versa for migration or nomadism. However, spatiotemporal heterogeneity did not explain the differentiation between nomadic and migratory individuals. We found that climate and anthropogenic features influenced individual movements: elk were more likely residents if they experienced more mild winters, and pronghorn were more likely residents if they resided closer to roads. Our findings demonstrate that ungulate movement strategies are consistently linked to spatiotemporal resource variation across scales and identify additional mechanisms for localized behavioral differences.

Decade-scale ecological datasets provide critical insights into long-term ecosystem properties, and long-term ecosystem response to human driven landscape alterations. In the state of Mississippi, USA, a history of intensive deforestation between 1830 and 1920 was followed by intensive sediment mitigation measures including intentional channel straightening and dredging and widespread reforestation. These corrective actions led to widespread and sometimes catastrophic channel incision and the potential for decoupling of floodplain and channel aquatic ecosystems. In this dataset we document a quantitative multi-decadal fish community and fish habitat dataset for 762 samples from streams draining National Forests in Mississippi. These data are used in a companion manuscript to test the hypothesis that increased channel incision relates to decreased prevalence of species with ecologies indicating floodplain, backwater, or off-channel habitat use. We provide data for associated landscape-level covariates (land use, stream network topology) derived from remote sensing data sources. We further provide a literature-based database of resource use for each species encountered in the survey. Scripts which document analyses of channel-floodplain ecological decoupling in an associated manuscript (Stearman et al. 2025) and code required to run these scripts are also provided.

This dataset consists primarily of amplitude values (dBA re 20 µPa) of sounds made by birds in Utqiagvik, Alaska, during June 2-22, 2024, as measured using a LATNEX sound pressure level (SPL) meter (SM-130DB, fast time integration). Each measurement is the maximum SPL measured during an individual call or song produced by a bird. These measurements were made in the open tundra opportunistically when birds were calling in the near-field (i.e., less than 50 meters distance from the measurer). Measurements were not made when multiple animals were calling, or when other background noises (e.g., planes, cars, human voices, or wind) were present.

The Sonoran Desert Toad (Incilius alvarius) is the only animal known to secrete the psychedelic compound 5-MeO-DMT as a chemical defense, but the source of 5-MeO-DMT in I. alvarius remains unknown. Some amphibians produce chemical defenses endogenously or through symbiotic interactions, while others acquire them from specialized diets. In this study, we analyzed toxin gland secretions and diet profiles from wild I. alvarius and sympatric anurans from native and urban habitats around Tucson, Arizona, to explore possible links between diet and 5-MeO-DMT production. All I. alvarius secreted high concentrations of 5-MeO-DMT, whereas other sympatric toads did not. The diet of I. alvarius was similar to that of sympatric anurans, indicating that I. alvarius does not exhibit relative dietary specialization. Slight dietary differences between I. alvarius in native and urbanized habitats were observed. Taken together, these lines of evidence suggest that diet is not directly linked to 5-MeO-DMT production, and support the alternative hypotheses that I. alvarius Sonoran Desert toads synthesizes 5-MeO-DMT endogenously, or via a microbial symbiont.

Population viability analysis (PVA) can be a useful decision-support tool to leverage uncertainty to avoid conservation hesitancy and paralysis. We developed a novel PVA model to help evaluate the effectiveness of a range of ex situ management options for the Critically Endangered Poweshiek skipperling butterfly.  The PVA indicated that the last three known United States populations face high likelihoods of extinction in the absence of supportive ex situ management, particularly when population sizes and in situ survival rates are low. Modeling indicated that a headstarting program initiated in 2017 to reinforce these populations was only likely delaying extirpation. Persistence probabilities fell once the program was concluded, regardless of population size or survival rate. An alternative ex situ breeding program provided significant boosts to the persistence of all populations by producing significantly more individuals available for releases than a headstarting program reliant on in situ population sizes could provide. Withholding individuals to establish a large ex situ breeding population did not impose a notable penalty to wild populations and improved persistence. Persistence was boosted further when an ex situ breeding program is combined with headstarting to reinforce populations. Based on these model outcomes, we elected to pivot management strategies from headstarting to reinforcement via an ex situ breeding program.  Effective PVAs are contingent on the incorporation of as much information as possible, acknowledgement of uncertainty, and flexibility. PVAs provide research opportunities and have been under-utilized in insect conservation. Our model is likely the first to link ex situ management to in situ dynamics for an invertebrate.

Aquila chrysaetos (Golden Eagles) are long-lived top predators, vulnerable to a variety of threats. There is increasing concern about the declining population in coastal southern California, which has largely coincided with habitat loss due to urbanization of the region. This Mediterranean-type ecosystem is also experiencing more prolonged and intense droughts, which can reduce the abundance of key prey species, such as jackrabbits (Lepus californicus) and ground squirrels (Otospermophilus beecheyi). However, the impact of drought on Golden Eagles is poorly understood. Here, we used high-resolution GPS tracking data to calculate eagle home ranges and hypothesized that home range size would be influenced by drought such that home ranges would be larger to meet their resource needs with worsening drought severity. Fifty individuals were captured over seven breeding seasons, spanning the time both during and after a historic drought. We also compared space use for different stages of the breeding season throughout each year. Golden Eagle home ranges increased by 77% during extreme drought compared to wetter conditions. Drought-breaking rainfall corresponded with much smaller home ranges compared to home range sizes during drought years. As drought is projected to be more prolonged and frequent in this region with climate change, this may result in increasingly large home range sizes at the same time as eagles are facing ongoing habitat loss and fragmentation from various land use changes. Our results suggest that the frequent and severe drought that is projected for this region could lead to lowered nesting density and increase the risk of further population decline.

Both sexes of Whiskered Auklets (Aethia pygmaea) display the most elaborate feather ornaments of any seabird: a slender black forehead crest, and 3 bilaterally symmetrical pairs of white facial plumes (superorbital, suborbital, and auricular). We studied patterns of ornament variation in 796 banded individuals (147 of known sex, 254 of known age from 1 to 16 years) during 1992–2009 at Buldir Island (principally), and 3 other Aleutian Islands (Davidof, Ulak, and Egg) in Alaska, USA. As expected for socially selected traits, ornaments were more variable across individuals than anatomical traits in size, but with only slightly male-biased sexual dimorphism. Body condition index increased from age 1 to 3 years but changed little thereafter. Even within birds ≥4 years old, ornament size was positively related to body condition index. Subadults (one-year-olds) had smaller ornaments than adults (age 2–16 years), but there was no further change in ornament size as adults aged and no evidence of senescence even in the oldest birds (>8 years old). Nonetheless, overall ornament size varied from year to year at Buldir and was correlated with indices of both ocean climate and auklet productivity in the preceding 2–5 years. From Buldir to Egg Island (1,266 km), the size of both anatomical and ornamental traits increased by 5–15% except for bill depth, which was largest in birds from Buldir and Egg at opposite ends of the Aleutian breeding range. This study is one of the few to examine patterns of ornament variation in a long-lived, socially monogamous bird, even though such patterns are crucial to understanding the relationship between sexual selection and life history.

Habitat is a key aspect of any species’ niche and can affect populations at multiple spatial scales. Basic ecology and effective conservation thus require understanding which habitats matter and at which scales. Yet, habitat studies are rarely scale-optimized and what determines the scale(s) at which populations are affected by surrounding habitat (the “scale of effect”) is poorly understood. In this study, we test the “mobility hypothesis,” which predicts that species with larger foraging ranges should have larger scales of effect. The mobility hypothesis is the most popular explanation of what determines species’ scales of effect but empirical support is mixed. We test the mobility hypothesis using wild bee species and, in doing so, also assess landscape-scale habitat associations of 84 bee species. We collected 30,376 specimens of 84 bee species from 165 sites in the northeastern USA and used linear models to determine landcover associations and scales of effect for each species. To test the mobility hypothesis, we asked whether scales of the effect varied with two mobility-related traits - body size or sociality, which are the strongest known predictors of bee foraging ranges. Controlling the false discovery rate at 5%, we found 193 significant species-landcover associations across 60 (of 84) species. Scales of effect ranged from 100 to 8000 m (mode = 200 m; median = 1000 m) and – counter to the mobility hypothesis – were not associated with body size or sociality. As a result, we argue that ecologists should reconsider making assumptions about species’ scales of effect and should instead explicitly measure scales of effect for their particular study organism and system. Considering the landcover associations themselves, we found these were broadly explained by phenology, with spring-flying bees being associated with forests and summer-flying bees being associated with more open, non-forested habitats.

Declines in migratory landbird populations require targeted research to identify population-limiting factors acting throughout the annual cycle. Tracking studies provide data on migration timing and speed, which have been used to describe carryover effects of nonbreeding habitat use. To explore how variation in precipitation and forest cover among nonbreeding sites influenced departure dates and migration speed in Vermivora chrysoptera (Golden-winged Warbler), we fitted 69 birds with radio transmitters in Costa Rica and tracked them via the Motus Wildlife Tracking System. Capture sites covered a broad gradient of precipitation and forest cover and were separated by <100 km. The datasets contained herein include departure dates and migration durations for birds tracked via Motus and related data for each individual, including capture location, age, sex, and Motus tag ID. For each capture location in Costa Rica, we extracted precipitation values from Worldclim and estimated forest cover around locations in QGIS (see methods below).