We identify key human threats and evaluate how threat intensity, defined as the probability of a given threat being used to justify listing a species under the U.S. Endangered Species Act (ESA), changes through time. We collected data on threats occurrence for 1,550 species listed under ESA between 1975 and 2020, from which we identified six major threats. We are first to show that the threat intensity for pollution peaked in 2000 but is now declining, which we hypothesize to be a result of the Clean Water and Clean Air Acts. We also showed that the threat intensity for environmental stochasticity (variation in climate) and species-species interactions (exotic-species interactions) has steadily increased to where these threats are now among the top threats, and that threat intensity for habitat modification was top in 1975 as it is today. Looking at the species-species interactions threat through finer lenses, we investigate the effects of exotic organisms on species listed under the ESA. Counter to our predications, preliminary analyses suggest that while species from all over the world have an influence on endangerment of North American species, some major culprits are species native to the eastern U.S who were released in the western United States and that exotic organisms affect over 40% and 90% of all listed species and those found on Pacific Islands, respectively. Together, our findings provide support that current environmental laws keep species among us, that there should be increased focus on protecting these legislations, and that funding needs to be allocated to reduce habitat loss and the spread of exotic species. 

We evaluate how human-induced habitat fragmentation affects the distribution of vertebrates and insects. We use long-term data to relate changes in site occupancy (i.e., the probability of given species to occupy a given site) to human induced changes in the landscape or seascape. We use statistical models that adjust occupancy estimates of vertebrates and insects by the probability of false negatives. Our research identified that human actions occurring at spatial extents between 0.5 – 5 km from a wetland or pond reduce the occupancy for frogs. We also found that occupancy of the diamondback terrapin (Malaclemys terrapin) in the Chesapeake Bay not only negatively relates to shoreline armoring and density of ghost cab-pots, but also to the amount of agricultural land within 0.5 km of a shoreline. Our research also established that browsing of understory forest vegetation by over-abundant white-tailed deer (Odocoileus virginianus) populations negatively correlates with forest-bird and butterfly occupancy and positively with the prevalence of a tick-borne disease, Ehrlichiosis. Our research provides input for regional conservation planning where our research identifies key areas that need to be conserved or managed to increase population viability for species of conservation concern in Virginia. 

At local extent we study movement ecology of frog and birds. We investigate movement patterns of toads and birds using technology used to find avalanche victims. We found that toads roam great distances from their breeding ponds, with distances exceeding 200 m, and that individuals within a given species vary drastically in habitat use – some prefer cavities whereas others bury themselves in the leaf litter. For the wood thrush (Hylocichla mustelina), a migrant bird species of conservation concern, we were first to show that habitat use of roosting individuals at night differs from the habitat they use during the day. Together these studies show that the currently required forest buffer around ponds and wetlands are insufficient to conserve frogs and toads and that management of bird populations requires simultaneous evaluation of habitat use during the day as well as at night. We will continue our research in movement ecology, as we know relatively little where species occur once breeding commences, which for frogs and toads typically exceeds 10 months.