1. Prey utilization by barn owls (Tyto alba) Dustin Kern Department of Biological Sciences, York College of Pennsylvania Objective Results Conclusions 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. Introduction The barn owl (Tyto alba) is an iconic farmland bird that has been associated with humans and agriculture for centuries (Bunn et al., 1982). Owl pellets have been utilized in many studies to determine owl food habits, which naturally contain small mammals, particularly rodents (Pearson and Pearson, 1947). 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. Literature Cited 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 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. To determine if Barn Owls living near humans, incorporate rats (a rodent pest) in their diet. Species Type M.H.S. July 2011 Ziegler’s January 2012 Halby’s February 2012 Ziegler’s March 2012 Ziegler’s June 2012 Ziegler’s October 2012 Total Species (%) Meadow Vole79.4 (54) a 70.2 (33)84.1 (37)79.8 (83)90.5 (67)68.8 (66)78.5 (340) Short-tailed Shrew8.8 (6)12.8 (6)9.1 (4)8.7 (9)5.4 (4)11.5 (11)9.2 (40) House Mouse10.3 (7)4.3 (2)6.8 (3)3.8 (4)1.4 (1)7.2 (7)7.0 (24) White-footed Mouse1.5 (1)8.5 (4)0 (0)5.8 (6)2.7 (2)7.2 (7)5.8 (20) Rattus0 (0)4.3 (2)0 (0)1.9 (2)0 (0)5.2 (5)2.1 (9) Total15.7 (68)10.9 (47)10.2 (44)24.0 (104)17.1 (74)22.2 (96)433 Species TypeWeight (g)Skull Length (mm) Meadow Vole35-6025.8–28.8 Short-tailed Shrew15-3020.8–24.8 House Mouse15–2320.4–22.5 White-footed Mouse16–3024.1–27.4 Rattus140-28042.0–47.0 Table 1. Composition of prey (% and numbers) in the diet of Barn Owls in Dauphin County, PA. Table 2. Average weight and skull size of 5 rodent species caught by Barn Owls. a Number of specimens between parentheses. Methods The pellets were collected from 1 nest box and 2 roost sites, in Dauphin County, Pennsylvania, over the course of nearly one year. A dissection kit was used to break apart casting pellets. A skull key was used to classify small mammals found in pellets (DeBlase and Martin, 1981). Materials 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. Rattus Meadow Vole prudentialhomesale.com bookstore.ycp.edu kreuss.com A regurgitated owl pellet.Forceps used for dissectionComparison of skulls between 2 rodent species