Date of Award

Spring 5-15-2016

Document Type

Thesis

Department

Environmental and Forest Biology

Thesis Advisor

William M. Shields

Keywords

Snowy owls, Bubo scandiacus

Abstract

The snowy owl (Bubo scandiacus) is a charismatic raptor that exhibits irruptive movements to exploit unpredictable resources in the Arctic tundra. During irruption years, many owls migrate past the southernmost extent of their traditional wintering grounds and must adjust to entirely unfamiliar habitats. The conditions associated with these new habitats may impact aspects of snowy owl behavior, and may influence snowy owls’ abilities to adapt to their wintering grounds during irruption years. I analyzed the hunting success, hunting behaviors, and diurnal activities of winter irruptive snowy owls in New York, USA, from January-March, 2015, and assessed how environmental factors (temperature, time period, cloud cover, snow depth, habitat type, etc.) influence snowy owl hunting success and behavior. I used an online citizen science resource, eBird, to locate snowy owls and I observed them from an automobile. Snowy owls were successful in 45.1% of 51 prey capture attempts. Adult owls were 30% more successful in capturing prey than were juveniles. Snowy owls used variants of the sit-and-wait technique to capture mammalian prey. Owls executed hunting attempts more frequently at low temperatures than at high temperatures. Snowy owl hunting activity peaked during the morning and late afternoon. Snowy owls were more successful in capturing prey at 50-100% cloud cover than at 0-50% cloud cover. All other environmental factors had no detectable influence on snowy owl hunting success. When compared to previous studies, winter irruptive snowy owls were equally adapted to their wintering grounds as were wintering snowy owls during non-irruption years.

Included in

Ornithology Commons

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