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Journal of Ethology

, Volume 24, Issue 2, pp 147–154 | Cite as

Predictors of biting fly harassment and its impact on habitat use by feral horses (Equus caballus) on a barrier island

  • David M. Powell
  • David E. Danze
  • Michael A. Gwinn
Article

Abstract

Feral horses on Assateague Island, Maryland, were observed in June and August 2000 to determine what behavioral and ecological factors affect the intensity of biting fly harassment and whether habitat use by horses was influenced by biting flies. Fly counts and frequencies of comfort movements (i.e., movements designed to dislodge insects) were recorded during focal animal samples, as well as data on sex, group size, habitat type, temperature, humidity, wind speed, and behavior. Seasonal habitat use patterns were assessed using 7 years of monthly census data on the horses. The number of biting flies on the horse was affected by horse sex, habitat, temperature, and group size. The number of comfort movements a horse showed was affected by habitat, temperature, wind speed, group size, and number of horses within one body length of the focal. The number of comfort movements made by a horse was found to be highly correlated with fly numbers. Though marshes were used most throughout the year, the pattern of use of dune, scrub, and human-altered habitats reflects a pattern of biting fly avoidance and refuge-seeking by the horses.

Keywords

Horses Fly Barrier Island Habitat use Harassment 

Notes

Acknowledgements

We would like to thank Carl Zimmerman, Jack Kumer, and Alison Turner of the National Parks Service for their assistance with this research. Edward Barrows (Georgetown University) also provided helpful comments and assistance. The manuscript was improved by comments from two anonymous reviewers. This research was approved by the Georgetown University Animal Care and Use Committee.

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Copyright information

© Japan Ethological Society and Springer-Verlag 2005

Authors and Affiliations

  • David M. Powell
    • 1
  • David E. Danze
    • 2
  • Michael A. Gwinn
    • 3
  1. 1.Department of MammalogyWildlife Conservation Society, Bronx ZooBronxUSA
  2. 2.Administrative Management Systems Support Branch, Office of the Chief Technology OfficerSmithsonian InstitutionWashington DCUSA
  3. 3.Department of BiologyGeorgetown UniversityWashington DCUSA

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