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Artificial nightlight alters the predator-prey dynamics of an apex carnivore

Citation

Ditmer, Mark et al. (2020), Artificial nightlight alters the predator-prey dynamics of an apex carnivore, Dryad, Dataset, https://doi.org/10.5061/dryad.crjdfn32t

Abstract

Artificial nightlight is increasingly recognized as an important environmental disturbance that influences the habitats and fitness of numerous species. However, its effects on wide-ranging vertebrates and their interactions remain unclear. Light pollution has the potential to amplify land-use 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 land-use planning. Here, we combined satellite-derived estimates of light pollution, with GPS-data from cougars (Puma concolor; n = 56), mule deer (Odocoileus hemionus; n = 263), and locations of cougar-killed deer (n = 1,562 carcasses), to assess the effects of light exposure on mammal behavior and predator-prey relationships across wildland-urban 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 wildland-urban interface, but hunted them in the relatively darkest locations. Light had the greatest effect of all covariates on where cougars killed deer at the wildland-urban 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 wildland-urban 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.

Methods

The data provided here are the final datasets used in each of the primary models used in the manuscript "Artificial nightlight alters the predator-prey dynamics of an
apex carnivore". These data are the processed (as described in the manuscript) values derived from GPS-collared cougars, mule deer, and the cache site locations of cougar-killed mule deer. Additional summary data are available in tables and supplemental materials associated with this manuscript. GPS location data are owned by the Utah Division of Wildlife Resources, Nevada Department of Wildlife, and the National Park Service. In Utah, Nevada, and Arizona cougars and mule deer are legally classified as big game species. Due to the potential for abuse, location data are considered proprietary and protected under state law. As such, they are not publicly available in their raw format. Researchers interested in obtaining copies of these data can formally request access through a Government Records Access and Management Act (GRAMA) or similar mechanism submitted to the appropriate agency.  

Usage Notes

README files contain general info and column descriptions for the four main analyses reported in "Artificial nightlight alters the predator-prey dynamics of an
apex carnivore" by Ditmer et al. 2020 (Ecography; doi: 10.1111/ecog.05251). 

Resource selection function of mule deer cache sites: README_CacheRSF_ColumnDescriptions.txt | Data: CacheRSF.csv

Mule activity patterns: README_ActivityDeer_ColumnDescriptions.txt | Data: ActivityDeer.csv

Integrated step selection function models: README_StepSelectionFunctions_ColumnDescriptions.txt | Data: CougarSSF_NoHouseDenVariable.csv, CougarSSF_WithHouseDensity.csv, DeerSSF_NoHouseDenVariable.csv, DeerSSF_WithHouseDenVariable.csv

Assessing functional responses from light ratios of use vs. availability: README_FuncResponseRatios_ColumnDescriptions.txt | Data: CougarRatio.csv, DeerRatio.csv