Geology topics

Leah McTigue

Publications and source records attributed to Leah McTigue.

3 recordsLinked to original sources

USGS2024

Does daily activity overlap of seven mesocarnivores vary based on human development?

Many species of wildlife alter their daily activity patterns in response to co-occurring species as well as the surrounding environment. Often smaller or subordinate species alter their activity patterns to avoid being active at the same time as larger, dominant species to avoid agonistic interactions. Human development can complicate interspecies interactions, as not all wildlife respond to human activity in the same manner. While some species may change the timing of their activity to avoid being active when humans are, others may be unaffected or may benefit from being active at the same time as humans to reduce predation risk or competition. To further explore these patterns, we used data from a coordinated national camera-trapping program (Snapshot USA) to explore how the activity patterns and temporal activity overlap of a suite of seven widely co-occurring mammalian mesocarnivores varied along a gradient of human development. Our focal species ranged in size from the large and often dominant coyote ( Canis latrans ) to the much smaller and subordinate Virginia opossum ( Didelphis virginiana ). Some species changed their activity based on surrounding human development. Coyotes were most active at night in areas of high and medium human development. Red fox ( Vulpes vulpes ) were more active at dusk in areas of high development relative to areas of low or medium development. However, because most species were primarily nocturnal regardless of human development, temporal activity overlap was high between all species. Only opossum and raccoon ( Procyon lotor ) showed changes in activity overlap with high overlap in areas of low development compared to areas of moderate development. Although we found that coyotes and red fox altered their activity patterns in response to human development, our results showed that competitive and predatory pressures between these seven widespread generalist species were insufficient to cause them to substantially alter their activity patterns.

PLoS ONE↗

USGS2023

Influence of human development and predators on patterns of Virginia opossum occupancy, abundance, and activity

As human development continues to expand, wildlife must relocate or adapt to survive. Many mammalian mesopredators, such as the Virginia opossum ( Didelphis virginiana ), have adapted to living alongside human development. Furthermore, top-down predation pressure may be altered in nuanced ways within the human environment. Species such as opossums may be shielded from predation by human development or behavioral changes in predators. Understanding how dominant and subordinate mesopredators co-exist across natural and developed areas will provide insight into how wildlife communities are structured. Our objective was to evaluate how opossum occupancy, abundance, and activity were associated with human development and the relative abundance of their predators. We used data from a nationwide camera trapping study, Snapshot USA, to estimate opossum occupancy, abundance, and activity. We related these measures to the surrounding landscape and urbanization variables. We found that opossum occupancy was positively associated with anthropogenic sound (a surrogate for human activity). Furthermore, opossums in heavily forested areas were more likely to be detected in locations with higher predicted anthropogenic sounds. In areas with a high density of human housing, opossum relative abundance increased when predator abundance increased. We also found opossums were strictly nocturnal and shifted their activity to earlier in the evening in the presence of high predator abundance. Our results suggest that humans and their urban development can have multidimensional impacts on opossum behavior and occurrence, and could facilitate changes in predator–prey dynamics. Future research should evaluate if the association of opossums with urban areas is due to human-subsidized resources or caused by reduced mortality from altered predator–prey dynamics.

Journal of Zoology↗

USGS2023

Effects of landcover on mesocarnivore density and detection rate along an urban to rural gradient

Human development has major implications for wildlife populations. Urban-exploiter species can benefit from human subsidized resources, whereas urban-avoider species can vanish from wildlife communities in highly developed areas. Therefore, understanding how the density of different species varies in response to landcover changes associated with human development can provide important insight into how wildlife communities are likely to change and provide a starting point for predicting the consequences of those changes. Here, we estimated the population density of five common mesocarnivore species (coyote ( Canis latrans ), bobcat ( Lynx rufus ), red fox ( Vulpes vulpes ), raccoon ( Procyon lotor ), and Virginia opossum ( Didelphis virginiana) ) at 12 study sites along an urban to rural gradient in the greater Fayetteville Area, Northwest Arkansas, USA between November 2021, and March 2022. At each study site, we applied the Random Encounter Model (REM) to data from camera traps to calculate the density of five focal species. Coyote density ranged from 0.5 to 0.93 individuals/km 2 . Raccoon density ranged from 0.19 to 20.25 individuals/km 2 . Bobcat density ranged from 0 to 1.06 individuals/km 2 . Opossum density ranged from 0 to 3.43 individuals/km 2 . Red fox density ranged from 0 to 0.10 individuals/km 2 . Coyote and raccoon density showed a positive relationship with anthropogenic noise. Opossum density increased with HUD. Red Fox and bobcat density showed a negative relationship with forest area and a positive relationship with distance to water respectively, however confidence intervals for both species overlapped zero. The density estimates we report based on camera trap data of unmarked animals were consistent with reports from the literature for these same species derived from traditional methods, providing additional support to the REM as a viable, non-invasive method to calculate density of unmarked species. Our second analysis consisted of taking camera level density estimates and treating them as detection rates corrected for camera viewshed and animal movement. Coyote and raccoon detection rate showed a positive relationship with anthropogenic noise. Red Fox detection rate was positively related to developed open space, and negatively related to distance to water. Similarly to red fox, opossums detection rate was higher in areas with more developed open space. We found no evidence that bobcat density or detection rate varied with any of the landcover or anthropogenic variables we measured.

Arkansas↗