Tana L. Verzuh | Search USGS

USGS2026

Interacting effects of human presence and landscape modification on birds and mammals

Sustainable human–wildlife coexistence requires a mechanistic understanding of the many ways that humans affect animals. However, progress is hampered by the lack of accessible data measuring the dynamic presence of people. Here, we leverage mobile-device data to disentangle how human presence and landscape modification differentially influence the use of geographic and environmental space for 37 mammal and bird species across the United States. Human presence affected more than 65% of species, with substantial variation across species. For ~60% of species that responded to human activities, the effects were interdependent—animals tended to react more strongly to human presence in less modified habitats. Our results demonstrate that human presence and landscape modification have complex combined effects on wildlife, which need to be considered for effective management.

Science↗

USGS2025

Expression and mechanisms of behavioral plasticity in large mammals

Behavioral plasticity, the alteration of behavior in response to stimuli, is becoming increasingly important in the context of human-induced rapid environmental change. Theoretical and empirical studies suggest that the expression and magnitude of behavioral plasticity are likely facilitated or constrained primarily by two factors: environmental variation and endogenous traits such as body size. The contextual role of these factors on behavioral plasticity, however, is poorly understood; there are relatively few studies that have compared the magnitude and potential drivers of behavioral plasticity at different levels (i.e., population and individual) across species, especially in free-ranging animals with diverse behavioral traits such as large mammals. Here, we quantify and test potential hypotheses for the mechanisms underpinning behavioral plasticity at the individual and population level in response to variation in summer temperatures for 1068 animal-years in 17 populations across nine species of large mammals. All populations displayed behavioral plasticity in response to increased temperatures, modifying their relative selection for heat-relieving habitat attributes (e.g., elevation) and heat-generating behavior (i.e., movement speed). We found strong support for the hypothesis that the variability of the physical environment is an important driver of behavioral plasticity—both mean population behavioral plasticity and variation among individuals within each population in plasticity were lower with increased heterogeneity of habitat attributes such as tree cover. Yet, the variability in environmental conditions (i.e., the magnitude of the temperature increase) had no effect on behavioral plasticity within and among populations. We did not detect an effect of endogenous traits on the expression of behavioral plasticity; however, we note that data availability limited our tests of this hypothesis to a select few endogenous traits (body size, feeding guild, and sex of the tracked individuals) that predominantly vary at the species level, for which we had one to three replicate populations per species. Our results provide an integrative and generalizable understanding of the expression of behavioral plasticity among populations of large mammals in temperate environments and emphasize the important but nuanced role of environmental variation in determining the scope of behavioral plasticity in these populations.

Wyoming↗

USGS2025

Beyond habitat: Memory versus environment in shaping animal space use

For nearly half a century, ecologists have sought to explain animal space use through characteristics of the environment (i.e., habitat). Recent evidence suggests animals also use memory of previous experiences to decide when and where to move. Yet, the relative influence of the two in explaining animal space use has not been resolved. Using six large ungulate species in the Rocky Mountains (USA), we evaluated the performance of a habitat selection model with 16 environmental variables and another with two variables representing previous use (i.e., memory). While memory outperformed the environment for two species and the environment outperformed memory for four species, the influence of memory and the environment was overall comparable. The environment best explained the space use of specialists, while memory best explained species with strong site fidelity. Our work challenges traditional habitat selection theory, showcasing that animals build their spatial preferences through experience just as much as merely responding to their environment.

Wyoming↗