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

Mark A. Ditmer, David C. Stoner, Clinton D. Francis, Jesse R. Barber, James D. Forester, David M. Choate, Kirsten E. Ironside, Kathleen M. Longshore, Kent R. Hersey, Randy T. Larsen, Brock R. McMillan, Daniel D. Olson, Alyson M. Andreasen, Jon P. Beckmann, P. Brandon Holton, Terry A. Messmer, Neil H. Carter

Research output: Contribution to journalArticlepeer-review


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 = 1562 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.

Original languageEnglish (US)
Pages (from-to)149-161
Number of pages13
Issue number2
StatePublished - Feb 2021

Bibliographical note

Funding Information:
– This project was generously funded by NASA (grant nos. NNX17AG36G and NNH10ZDA001N), National Park Service, U.S. Geological Survey, Utah Division of Wildlife Resources, Nevada Dept of Wildlife, Arizona Game and Fish Dept, Dept of Energy, Bureau of Land Management, U.S. Forest Service, USDA Wildlife Services and U.S. Fish&Wildlife Service. Data collected using USGS funding are available under Ironside ( ). Subsidiary funding was provided by Utah Army National Guard, Kennecott Utah Copper Corporation, the African Safari Club of Florida, Utah's Hogle Zoo, the Utah Chapter of the American Association of Zoo Keepers, Carson Valley Chukar Club, Shepreth Wildlife Park, Dugway Proving Ground, Grand Canyon Conservancy, Grand Canyon Trust, Johnson Family Foundation, Mule Deer Foundation, Nevada Agricultural Experiment Station, Nevada Bighorns Unlimited, Nevada Division of State Lands, Lake Tahoe License Plate Grant, Northern Nevada Chapter of the Safari Club, Rocky Mountain Elk Foundation, Safari Club International, Summerlee Foundation, Sportsman for Fish and Wildlife, Utah Archery Association and Wildlife Conservation Society. Funding

Publisher Copyright:
© 2020 The Authors. Ecography published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos


  • ecological disturbance
  • movement ecology
  • sensory ecology
  • sensory pollution
  • wildlife

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