17 research outputs found
Cougar Dispersal and Natal Homing in a Desert Environment
We present a review of cougar dispersal literature and the first evidence of natural (i.e., unmanipulated) homing behavior by a dispersing male cougar (Puma concolor) that sustained severe injuries crossing the northern Mojave Desert. Based on Global Positioning System and ground tracking data, the male traveled a total distance of 981.1 km at 5.03 km/d, including 170.31 km from the Desert National Wildlife Refuge to the northwestern Grand Canyon, where he sustained severe injuries. The interkill interval increased from 7.1 ± 2.7 d while he was in his natal range to 17.5 ± 4.9 d during dispersal. While homing, the male appeared to consume only reptiles until he died, 33.7 km from his capture site. In desert environments where prey availability is low, homing behavior may be an important strategy for dispersing cougars, providing a mechanism for persistence when the best quality habitats they encounter are already occupied by adult residents. Therefore, managing for habitat connectivity can ensure successful homing as well as dispersal on a greater scale than has been previously suggested. Elucidating the mechanisms that trigger homing during dispersal may provide critical insight into animal movements often overlooked as mundane behavior
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
Mule Deer Abundance, Cougar Home Range, and Predator-Prey Density Across a climatic Gradient in the Intermountain West
Spatial Responses to Climate Across Trophic Levels: Modeling Plants, Prey, and Predators in the Western United States
Coupling Mammalian Demography to Climate Through Satellite Time-Series of Plant Phenology
Climatically Driven Changes in Primary Production Propagate through Trophic Levels
Climate and landâuse change are the major drivers of global biodiversity loss. Their effects are particularly acute for wideâranging consumers, but little is known about how these factors interact to affect the abundance of large carnivores and their herbivore prey. We analyzed population densities of a primary and secondary consumer (mule deer, Odocoileus hemionus, and mountain lion, Puma concolor) across a climatic gradient in western North America by combining satelliteâbased maps of plant productivity with estimates of animal abundance and foraging area derived from Global Positioning Systems telemetry data (GPS). Mule deer density exhibited a positive, linear relationship with plant productivity (r2 = 0.58), varying by a factor of 18 across the climateâvegetation gradient (range: 38â697 individuals/100 km2). Mountain lion home range size decreased in response to increasing primary productivity and consequent changes in the abundance of their herbivore prey (range: 20â450 km2). This pattern resulted in a strong, positive association between plant productivity and mountain lion density (r2 = 0.67). Despite varying densities, the ratio of prey to predator remained constant across the climatic gradient (mean ± SE = 363 ± 29 mule deer/mountain lion), suggesting that the determinacy of the effect of primary productivity on consumer density was conserved across trophic levels. As droughts and longer term climate changes reduce the suitability of marginal habitats, consumer home ranges will expand in order for individuals to meet basic nutritional requirements. These changes portend decreases in the abundance of largeâbodied, wideâranging wildlife through climatically driven reductions in carrying capacity, as well as increased humanâwildlife interactions stemming from anthropogenic land use and habitat fragmentation