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1 October 2010 Cattle or Sheep Reduce Fawning Habitat Available to Columbian Whitetailed Deer in Western Oregon
Winston P. Smith, Bruce E. Coblentz
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We studied responses of Columbian white-tailed deer (Odocoileus virginianus leucurus) to cattle and sheep in western Oregon because of viability concerns. We used radio-telemetry, observations from horseback, and searches with a trained dog to determine fawning habitat, dam home ranges, and habitat use by fawns. Dams (n = 12) shifted (fi01_315.gif = 366 m, P < 0.05) their center of activity by establishing disjunct areas of use prior to fawning. Ten dams exhibited their largest Euclidian movement during May—July; 7 females undertook extended (fi01_315.gif = 1445 m) forays during spring. Three natal sites averaged 1926 m from the center of the dam's annual home-range. Dams avoided (P < 0.05) areas with livestock during fawning; 3 fawns were encountered during 243 h of searching (1 fawn/91.4 h) in areas with livestock stocking levels of ≥2.5 animal use month/ha (AUM), whereas 39 fawns were encountered during 275 h of searching (1 fawn/7.1 h) in areas with <2.5 AUM of livestock use. Natal areas (n = 52) were in denser luxuriant vegetation, typically along a permanent stream with greater obstruction to vision. Areas with cattle (Bos taurus) or sheep (Ovis aries) had lower percent vegetative cover, less diverse herbaceous vegetation, and less concealment cover. Establishing separate home ranges during the fawning season apparently was a response to the presence of livestock or effects of grazing, which reduced the vertical vegetation profile and concealment cover. Dams likely increase fawn survival by selecting sites with nutritious, palatable forage, denser vegetation, and moderate microclimates during parturition and lactation.

Winston P. Smith and Bruce E. Coblentz "Cattle or Sheep Reduce Fawning Habitat Available to Columbian Whitetailed Deer in Western Oregon," Northwest Science 84(4), 315-326, (1 October 2010).
Received: 29 January 2010; Accepted: 1 June 2010; Published: 1 October 2010

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