Date of Award:

5-1998

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

Kimberly A. Sullivan

Committee

Kimberly A. Sullivan

Committee

James A. Gessaman

Committee

Edmund D. Brodie Jr.

Abstract

My research primarily focused on the survival of short-eared owls (Asio flammeus) from leaving the nest until their emigration from their natal territories during 1993 and 1994. I attached tarsal-mounted radio transmitters to nestlings prior to fledging. Of 25 fledgling short-eared owls monitored, 16 (64%) died prior to dispersal and one (4%) died after dispersing. Mammalian predation (5, 29.4%) was the primary cause of mortality followed by starvation (4, 23.5%), exposure (2, 11.8%), auto collision (1, 5.9%), burial (1, 5.9%), and unknown causes (4, 23.5%). Hatch date was found to be negatively correlated with fledgling survival.

A secondary focus of my research was the breeding season diet of short-eared owls based on the identification of 704 prey items. The diet was dominated by small mammals (98.4%), primarily Great Basin pocket mice (Perognathus parvus, 33.8%), deer mice (Peromyscus maniculatus, 31.1%), Ord's kangaroo rats (Dipodomys ordii, 12.8%), and mountain voles (Microtus montanus, 12.5%). A significant change in prey proportions was observed between 1993 and 1994 and also with distance from the nesting site to irrigated agricultural land.

During 1994, I evaluated a mist net technique for capturing adult short-eared owls during the breeding season, capturing seven adults in 25 attempts.

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