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1 March 2011 The Winter Diet of Short-eared Owls in Subtropical Texas: Do Southern Diets Provide Evidence of Opportunism?
Damon Williford, Marc C. Woodin, Mary Kay Skoruppa
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Winter diet of the Short-eared Owl (Asio flammeus) in Texas is little known. We investigated the diet of Short-eared Owls wintering in McMullen County, in subtropical Texas, by analyzing the contents of 129 pellets collected over two winters (28 November 2007 to 22 February 2008 and 11 December 2008 to 11 February 2009) and conducted a latitudinal-based comparison of published diet studies of Short-eared Owls. In southern Texas, we recovered the remains of 162 prey items, 98% of which were vertebrates. Hispid cotton rats (Sigmodon hispidus) were the most important prey species in terms of percent of total number (67%) and percent of total biomass (87%). Most (86%) Short-eared Owl diet studies (based on ≥100 pellets) have been conducted north of 35°N, with only six studies, including the present study, conducted at or south of 35°N latitude. Voles (primarily Microtus spp.) were the dominant prey in North American studies (71%), but microtines were not the dominant prey in any of the six studies conducted south of 35°N latitude. We suggest that Short-eared Owls do not specialize on microtines, as is often implied, but rather depend on rodents with cyclic populations, such as the hispid cotton rat in southern areas.

Damon Williford, Marc C. Woodin, and Mary Kay Skoruppa "The Winter Diet of Short-eared Owls in Subtropical Texas: Do Southern Diets Provide Evidence of Opportunism?," Journal of Raptor Research 45(1), 63-70, (1 March 2011).
Received: 15 April 2010; Accepted: 1 October 2010; Published: 1 March 2011

Asio flammeus
Latitudinal variation
short-eared owl
Sigmodon hispidus
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