Sponsor
Portland State University. Department of Biology
First Advisor
Richard B. Forbes
Date of Publication
2-18-1976
Document Type
Thesis
Degree Name
Master of Science (M.S.) in Biology
Department
Biology
Language
English
Subjects
Mammals -- Columbia River, Mammals -- Oregon -- Willamette River, Island animals
DOI
10.15760/etd.2359
Physical Description
1 online resource. Digitized typeset
Abstract
A survey of small mammals on eight islands in the Columbia and Willamette Rivers near Portland, Oregon was conducted in 1974. The islands were Govermnent , Sand, Lemon, McGuire and Sandy Islands in the Columbia River and East, Ross and Hardtack Islands in the Willamette River. The objectives of the study were to ascertain and compare the kinds, distribution and relative densitites of small mammals . A variety of traps was used to capture the animals including Museum Special Rodent Traps , back- break mouse traps, scissor and guillotine- type stab mole traps , Sherman traps , modified Young traps and pitfalls . Most traps were set in linear transects . Trapping was conducted with the objective of sampling the major habitats on each island. Observations of scats, tracks , burrows and dead animals were also noted. One species of small marmnal , Sorex vargrans , was found on all eight islands . Microtus was found on five islands and Peromyscus maniculatus on four islands . Two islands yielded Scapanus townsendii. Glaucomvs sabrinus was found on only one island. I hoped that evidence would be found to prove or disprove that current theories of island biogeography would apply to river islands. However, data in this study were inadequate to allow calculation of precise indices of population densities . Therefore, I was unable to determine if theories of island biogeography do apply to these river islands.
Rights
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Persistent Identifier
http://archives.pdx.edu/ds/psu/15612
Recommended Citation
Kirk, Gayle, "A Survey of Small Mammals on Islands in the Columbia and Willamette Rivers" (1976). Dissertations and Theses. Paper 2362.
https://doi.org/10.15760/etd.2359