Changes in fox squirrel anti-predator behaviors across the urban–rural gradient

Abstract

Predator stimuli created by humans in the urban environment may alter animals’ anti-predator behaviors. I hypothesized that habituation would cause anti-predator behaviors to decrease in urban settings in response to humans. Additionally, I hypothesized that populations habituated to humans would show reduced responses to other predator stimuli. I observed three populations of squirrels (urban, suburban and rural) responses to human approaches, red-tailed hawk vocalizations (Buteo jamaicensis) and coyote (Canis latrans) vocalizations. Mahalanobis distances of anti-predator behaviors in response to human approaches were consistent with the urban–rural gradient. Flight initiation distances (X 2 = 26.33, df = 2, P < 0.001) and amount of time dedicated to anti-predator behavior (X 2 = 10.94, df = 2, P = 0.004) in response to human approaches were also consistent with the urban–rural gradient. Supporting the habituation hypothesis, naive juvenile squirrels increased flight initiation distances (X 2 = 35.89, df = 1, P < 0.001) and time dedicated to anti-predator behaviors (X 2 = 9.46, df = 1, P = 0.002) relative to adult squirrels in the same urban environment. Time dedicated to anti-predator behaviors differed among all three sites in response to both coyote (X 2 = 9.83, df = 2, P = 0.007) and hawk (X 2 = 6.50, df = 2, P = 0.035) vocalizations. Responses to both vocalizations on rural sites (coyote = 45%, hawk = 55%) greater than twice that found on the urban sites (coyote = 11%, hawk = 20%). This is possibly the first case of a transfer of habituation demonstrated under field conditions.

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Acknowledgments

I would like to thank Roel R. Lopez and Nova J. Silvy for their support during this project. I am grateful to Jane Packard who helped me formulate the ideas for this project. I would also like to thank the anonymous reviewers of this manuscript whose constructive criticism and editing suggestions greatly improved it. Thanks are extended to the undergraduate students whose hard work and dedication made this project possible. I also want to make a special note of the contributions of S. Kahlich and L. Gallant, whose countless hours trapping, and tracking fox squirrels made them invaluable. Funding and support was provided by the Ed Rachel Foundation and the Texas Agricultural Experiment Station.

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Correspondence to Robert A. Mccleery.

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Mccleery, R.A. Changes in fox squirrel anti-predator behaviors across the urban–rural gradient. Landscape Ecol 24, 483 (2009). https://doi.org/10.1007/s10980-009-9323-2

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Keywords

  • Anti-predator behavior
  • Vigilance
  • Squirrel
  • Urban
  • Urban–rural gradient