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Prey utilization by barn owls (Tyto alba) Dustin Kern Department of Biological Sciences, York College of Pennsylvania prudentialhomesale.com Introduction Materials Methods • The barn owl (Tyto alba) is an iconic farmland bird that has been associated with humans and agriculture for centuries (Bunn et al., 1982). • The pellets were collected from 1 nest box and 2 roost sites, in Dauphin County, Pennsylvania, over the course of nearly one year. • Owl pellets have been utilized in many studies to determine owl food habits, which naturally contain small mammals, particularly rodents (Pearson and Pearson, 1947). • A dissection kit was used to break apart casting pellets. • Rodent infestations continue to cause considerable property damage and produce health risks in urban and rural farmland (Albert et al., 2009). • Anticoagulant rodenticides are frequently used to control rodent pests (such as rats), but poisoning of non-target wildlife has been linked to such practices, including secondary poisoning of birds of prey, particularly owls (Newton et al., 1990). • Rural applications of anticoagulant rodenticides consumed by Barn Owls, induce lethal hemorrhaging after feeding on contaminated rats (Stone and Okoniewski, 1999). • This study utilizes pellet analysis, derived from previous field experiments to determine whether barn owls are catching rats that could potentially be poisoned by anticoagulant rodenticides. bookstore.ycp.edu kreuss.com • A skull key was used to classify small mammals found in pellets (DeBlase and Martin, 1981). Results Table 2. Average weight and skull size of 5 rodent species caught by Barn Owls. Weight (g) 35-60 15-30 15–23 16–30 140-280 • The entirety of the diet of Barn Owls in this study consists of rodents. • Analysis of regurgitated pellets showed that meadow voles were the most common prey at all sites and dates. • Although Rattus occurred in some pellet collections, they made up only a small part of the diet (2.1%) of Barn Owls at all sites and dates. Literature Cited Table 1. Composition of prey (% and numbers) in the diet of Barn Owls in Dauphin County, PA. M.H.S. Ziegler’s Halby’s Ziegler’s Ziegler’s Ziegler’s Total Species Type July January February March June October Species 2011 2012 2012 2012 2012 2012 (%) Meadow Vole 79.4 (54)a 70.2 (33) 84.1 (37) 79.8 (83) 90.5 (67) 68.8 (66) 78.5 (340) Short-tailed Shrew 8.8 (6) 12.8 (6) 9.1 (4) 8.7 (9) 5.4 (4) 11.5 (11) 9.2 (40) House Mouse 10.3 (7) 4.3 (2) 6.8 (3) 3.8 (4) 1.4 (1) 7.2 (7) 7.0 (24) White-footed Mouse 1.5 (1) 8.5 (4) 0 (0) 5.8 (6) 2.7 (2) 7.2 (7) 5.8 (20) Rattus 0 (0) 4.3 (2) 0 (0) 1.9 (2) 0 (0) 5.2 (5) 2.1 (9) Total 15.7 (68) 10.9 (47) 10.2 (44) 24.0 (104) 17.1 (74) 22.2 (96) 433 aNumber of specimens between parentheses. Species Type Meadow Vole Short-tailed Shrew House Mouse White-footed Mouse Rattus Conclusions Skull Length (mm) 25.8–28.8 20.8–24.8 20.4–22.5 24.1–27.4 42.0–47.0 • Albert, C. A., Wilson, L. K., Mineau, P., Trudeau, S., and Elliott, J. E. 2010. Anticoagulant rodenticides in three owl species from western Canada, 1988–2003. Archives of environmental contamination and toxicology, 58(2), 451-459. • Bunn, D. S., Warburton, A. B., and Wilson R. D. S. 1982. The Barn Owl. T. & A. D. Poyser: Berkhamsted, England. • DeBlase. A.F., and Martin, R.E. 1981. A Manual of Mammalogy with Keys to Families of the World. Wm. C. Brown Company Publishers, Dubuque, IA. • Newton, I., Wyllie, I., and Freestone, P. 1990. Rodenticides in British barn owls. Environmental pollution, 68(1), 101-117. • Pearson, O. P., and A. K. Pearson. 1947. Owl predation in Pennsylvania with notes on the small mammals of Delaware County. J. Mammal. 28: 137-147 Objective • To determine if Barn Owls living near humans, incorporate rats (a rodent pest) in their diet. Rattus Meadow Vole A regurgitated owl pellet. Forceps used for dissection Comparison of skulls between 2 rodent species • Stone, W. B., and Okoniewski, J. C. 1999. Poisoning of wildlife with anticoagulant rodenticides in New York. Journal of Wildlife Diseases, 35(2), 187-193. Acknowledgements I would like to express thanks and appreciation to my Senior Thesis Mentor, Dr. Karl Kleiner for his excellent guidance during the completion of this research.