Urban Ecosystems

, Volume 18, Issue 2, pp 517–523 | Cite as

Differing vigilance among gray squirrels (Sciuridae carolinensis) along an urban–rural gradient on Long Island

  • Ronald J. SarnoEmail author
  • Michael Parsons
  • Angela Ferris


Urbanization has had far-reaching effects on the wildlife that have adapted to this novel landscape. Not only have wildlife endured shifts in ecosystem function as a result of urbanization, but in many areas there has been a fundamental behavioral change. This “urban wildlife syndrome” – the collection of observable traits of wildlife species undergoing urbanization – prompted us to examine the effect of urbanization on vigilance of eastern gray squirrels (Sciurus carolinensis). We hypothesized that squirrels in more urban locations, due to presumed higher squirrel density and familiarization with humans, would be less vigilant than squirrels in more rural sites. We assigned study sites (i.e. city parks) to one of four rank categories of urbanization based upon human population density. In contrast to our original hypothesis, squirrels in urban sites were more vigilant than squirrels in less urban areas. In fact this difference was punctuated by an approximate 42 % reduction between moderately urban and semi-rural habitats. Squirrel density had a positive, yet weak, effect on vigilance time. Elevated intraspecific aggression, unpredictable changes in vehicular and pedestrian traffic, and associated noise levels and disturbance in urban settings where squirrels occur, may be responsible for more variable and heightened states of vigilance in the urban setting.


Urban–rural gradient Squirrels Vigilance Foraging 



We thank the Biology Department at Hofstra University for supporting this project. We also thank Melissa Grigione for critically reviewing the MS in its later stages.

Conflict of interest

The authors declare they there is no conflict of interest.


  1. Adams LW, Van Druff LW, Luniak M (2005) Managing urban habitats and wildlife. In: Braun CE (ed) Techniques for wildlife investigations and management. Allen, Lawrence, pp 714–739Google Scholar
  2. Altmann J (1974) Observational study of behavior: sampling methods. Behav 49:227–267CrossRefGoogle Scholar
  3. Bekoff M (2007) The emotional lives of animals: a leading scientist explores animal joy, sorrow, and empathy, and why they matter. New World Library, Novato, CA, 215 ppGoogle Scholar
  4. Bowers M, Breland B (1996) Foraging of gray squirrels on an urban–rural gradient: Use of the GUD to assess anthropogenic impact. Ecol Appl 6:1135–1142CrossRefGoogle Scholar
  5. Brown JS (1999) Vigilance, patch use and habitat selection: foraging under predation risk. Evol Ecol Res 1:49–71Google Scholar
  6. Conover MR (1997) Wildlife management by metropolitan residents in the United States: practices, perceptions, costs, and values. Wildl Soc Bull 25:306–311Google Scholar
  7. Dantzer B, Boutin S, Humphries MM, McAdam AG (2012) Behavioral responses of territorial red squirrels to natural and experimental variation in population density. Behav Ecol Sociobiol 66(6):865–878CrossRefGoogle Scholar
  8. Distefano E (2005) Human–wildlife conflict worldwide: a collection of case studies, analysis of management strategies and good practices. Food and Agricultural Organization of the UnitedGoogle Scholar
  9. Ditchkoff SS, Saalfeld ST, Gibson CJ (2006) Animal behavior in urban ecosystems: modifications due to human-induced stress. Urban Ecosyst 9:5–12. doi: 10.1007/s11252-006-3262-3 CrossRefGoogle Scholar
  10. Fairbanks B, Dobson FS (2007) Mechanisms of the group-size effect on vigilance in Columbian ground squirrels: dilution versus detection. An Behav 73(1):115–123CrossRefGoogle Scholar
  11. Hazen B, Poche RM (1992) California ground squirrel field efficacy study using 0.005% chlorophacinone bait. Proceedings of the Fifteenth Vertebrate Pest Conference, Lincoln, NebraskaGoogle Scholar
  12. McCleery R (2009) Changes in fox squirrel anti-predator behaviors across the urban–rural gradient. Landsc Ecol 24:483–493CrossRefGoogle Scholar
  13. McDonnell MJ, Pickett STA (1990) Ecosystem structure and function along urban–rural gradients: an unexploited opportunity for ecology. Ecology 71:1232–1237CrossRefGoogle Scholar
  14. Messmer TA (2000) The emergence of human–wildlife conflict management: turning challenges into opportunities. Internat Biodet & Biodeg 45:97–102CrossRefGoogle Scholar
  15. Parker TS, Nilon CH (2008) Gray squirrel density, habitat, suitability and behavior in urban parks. Urban Ecosyst 11:243–255CrossRefGoogle Scholar
  16. Sokal RR, Rohlf FJ (1995) Biometry: the principles and practice of statistics in biological research, 3rd edn. W.H. Freeman, New York, NYGoogle Scholar
  17. U.S. Census Bureau. New York by Place and County Subdivision: Population, Housing Units, Area, and Density. U.S. Census Bureau, Census 2000 Summary.
  18. VanDruff LW, Bolen EG, San Julian GJ (1996) Management of urban wildlife. In: Bookhout TA (ed) Research and management techniques for wildlife and habits. Allen, Lawrence, pp 507–530Google Scholar
  19. Warren P, Tripler C, Bolger D, Faeth S, Huntly N, Lepczyk C, Meyer J, Parker T, Shochat E, Walker J (2006) Urban food webs: predators, prey and the people who feed them. Bull Ecol Soc Am Vol 87(4):387–393CrossRefGoogle Scholar
  20. Woodroffe R, Thirgood S, Rabinowitz A (eds) (2005) People and wildlife: conflict or coexistence? Cambridge University Press, Cambridge, UKGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Ronald J. Sarno
    • 1
    Email author
  • Michael Parsons
    • 2
  • Angela Ferris
    • 1
  1. 1.Department of BiologyHofstra UniversityHempsteadUSA
  2. 2.Department of BiologyState University New York, Empire State CollegeHartsdaleUSA

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