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Document Type

Thesis - University Access Only

Award Date

1998

Degree Name

Master of Science (MS)

Department

Wildlife and Fisheries Science

First Advisor

Lester D. Flake

Keywords

owls, idaho, environment, habitat, nests

Abstract

The Idaho National Engineering and Environmental Laboratory (INEEL) is a 2,315 km2 energy research and development site located on the Upper Snake River Plain of Southeast Idaho. Owl research was conducted on the site during the spring and summers of 1996-1997. Objectives were to: a) determine productivity, habitat use, and possible nest site selection factors of burrowing owls (Athene cunicularia ), b) verify the presence of small owl species including the boreal owl (Aegolius funereus), the northern saw-whet owl (A. acadicus), the western screech owl (Otus kennicottii), the flammulated owl (0. flammeolus), and the northern pygmy owl (Glaucidium gnoma), c) determine influence of environmental variables and broadcast intervals on long-eared owl (Asio otus) calling frequencies, and d) detem1ine the number of nesting long-eared owls adjacent to the Big Lost River to compare with 1975-1976 data. Sixteen active burrowing owl sites were located in 1996. Eight were reoccupied and an additional 14 sites were located on the INEEL in 1997. a 68% increase over the known population in 1976-1977 (Gleason 1978). Burrowing owl nesting success and productivity levels declined from 80% and 4.5 chicks/confirmed pair in 1996 to 38% and 0.95 chicks/confirmed pair in 1997. A wet spring may have contributed to lowered chick survival. Comparison of nest burrows and unused reference burrows in similar habitat to determine potential nest site selection factors yielded only one variable that approached significance: nearest perch distance. The nearest perch at nest sites was located further away from the burrow than the nearest perch at reference sites. Night-long surveys were conducted for small arboreal species. Presence of the northern saw-whet owl was verified by obtaining a tape recording of a vocalizing male. A boreal owl and a bird which may have been a western screech owl were heard, but tape recordings could not be obtained. The presence of flammulated owls could neither be confirmed nor denied, but the similarity of this species' calls to the calls of the long-eared owl suggests that flammulated owls reported by Hansen (1994) were likely Jong-eared owls. Long-eared owls were the most commonly heard species during night-long surveys. The most significant recorded factor affecting long-eared owl calling frequencies was the Julian date of the survey; late March and early April were peak calling periods. Long-eared owl calling frequencies in response to conspecific broadcast intervals versus silent intervals were not significantly different in 1996 nor 1997. Similarly, calling frequencies during conspecific broadcast intervals versus other species intervals were not significantly different in 1996. Long-eared owl numbers were high in l 996 and spontaneous calling precluded responses to survey broadcasts. However, in 1997 when long-eared owl populations were low, significantly lower calling frequencies were documented during playback of other species than during conspecific broadcasts. Playback of other species may have inhibited long-eared owl calling or conspecific broadcast may have incited it. The number of nesting long-eared owls adjacent to the Big Lost River in 1996 and 1997 (13 and 12. respectively), was higher than the number documented in 1975 and comparable to that in l 976 (3 and 16, respectively).

Library of Congress Subject Headings

Owls -- Idaho
Owls -- Habitat -- Idaho
Owls -- Nests -- Idaho

Description

Includes bibliographical references (page 68-77)

Format

application/pdf

Number of Pages

107

Publisher

South Dakota State University

Rights

Copyright © 1998 Natalie Fahler

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