19 research outputs found
Artificial Nightlight Alters the PredatorâPrey Dynamics of an Apex Carnivore
Artificial nightlight is increasingly recognized as an important environmental disturbance that influences the habitats and fitness of numerous species. However, its effects on wideâranging vertebrates and their interactions remain unclear. Light pollution has the potential to amplify landâuse change, and as such, answering the question of how this sensory stimulant affects behavior and habitat use of species valued for their ecological roles and economic impacts is critical for conservation and landâuse planning. Here, we combined satelliteâderived estimates of light pollution, with GPSâdata from cougars Puma concolor (nâ=â56), mule deer Odocoileus hemionus (nâ=â263) and locations of cougarâkilled deer (nâ=â1562 carcasses), to assess the effects of light exposure on mammal behavior and predatorâprey relationships across wildlandâurban gradients in the southwestern United States. Our results indicate that deer used the anthropogenic environments to access forage and were more active at night than their wildland conspecifics. Despite higher nightlight levels, cougars killed deer at the wildlandâurban interface, but hunted them in the relatively darkest locations. Light had the greatest effect of all covariates on where cougars killed deer at the wildlandâurban interface. Both species exhibited functional responses to light pollution at fine scales; individual cougars and deer with less light exposure increasingly avoided illuminated areas when exposed to greater radiance, whereas deer living in the wildlandâurban interface selected elevated light levels. We conclude that integrating estimates of light pollution into ecological studies provides crucial insights into how the dynamic human footprint can alter animal behavior and ecosystem function across spatial scales
Available data support protection of the Southwestern Willow Flycatcher under the Endangered Species Act
Climate Effects on Ungulate Abundance Migration, and Habitat Selction on the Colorado Plateau
Using Remotely Sensed Indices of Primary Production to Evaluate Large Mammal Abundance and Space Use in the Arid Southwestern United States
Ungulate Abundance Across a Latitudinal Gradient: Primary Production, Summer Precipitation, and Habitat Fragmentation
Spatio-Temporal Responses to Climate Across Trophic Levels: Macroscopic Observations of Plant Phenology and Animal Movement in the Western United States
Quantifying animal movement for caching foragers: the path identification index (PII) and cougars, Puma concolor
Abstract Background Many studies of animal movement have focused on directed versus area-restricted movement, which rely on correlations between step-length and turn-angles and on stationarity through time to define behavioral states. Although these approaches might apply well to grazing in patchy landscapes, species that either feed for short periods on large, concentrated food sources or cache food exhibit movements that are difficult to model using the traditional metrics of turn-angle and step-length alone. Results We used GPS telemetry collected from a prey-caching predator, the cougar (Puma concolor, Linnaeus), to test whether combining metrics of site recursion, spatiotemporal clustering, speed, and turning into an index of movement using partial sums, improves the ability to identify caching behavior. The index was used to identify changes in movement characteristics over time and segment paths into behavioral classes. The identification of behaviors from the Path Identification Index (PII) was evaluated using field investigations of cougar activities at GPS locations. We tested for statistical stationarity across behaviors for use of topographic view-sheds. Changes in the frequency and duration of PII were useful for identifying seasonal activities such as migration, gestation, and denning. The comparison of field investigations of cougar activities to behavioral PII classes resulted in an overall classification accuracy of 81%. Conclusions Changes in behaviors were reflected in cougarsâ use of topographic view-sheds, resulting in statistical nonstationarity over time, and revealed important aspects of hunting behavior. Incorporating metrics of site recursion and spatiotemporal clustering revealed the temporal structure in movements of a caching forager. The movement index PII, shows promise for identifying behaviors in species that frequently return to specific locations such as food caches, watering holes, or dens, and highlights the potential role memory and cognitive abilities play in determining animal movements