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Date of Award

Summer 2025

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Studies

Degree Name

Master of Arts (MA)

Department

Environmental Studies

First Advisor

Flower, Aquila

Second Advisor

Bauman, Jenise

Third Advisor

McLaughlin, John F., 1962-

Abstract

The island marble butterfly (Euchloe ausonides insulanus) is an extremely endangered butterfly found only on islands in the Salish Sea ecoregion. The butterfly relies on coastal prairies for habitat; these prairies have become extremely rare because of habitat destruction, severely limiting the amount of available habitat for the butterfly, which now exists at a single site on a single island. Species that only exist at a single site face a high risk of extinction, so finding more habitat for the island marble butterfly is a crucial component of its conservation. I created habitat suitability models to find more habitat for the butterfly in the Salish Sea ecoregion. These models indicate that the fundamental niche of the butterfly is primarily limited by precipitation and that suitable habitat for the butterfly is limited to areas where its host plants can grow within the rainshadows of the Olympic Mountains and Vancouver Island Ranges. Much of the highest-quality potential habitat is located in the San Juan Islands and on Whidbey Island, but additional potential habitat exists on the Olympic Peninsula and Vancouver Island. Because most potential habitat for the butterfly is located in and around agricultural fields, cooperation with farmers is essential for the butterfly’s conservation. While the island marble may be able to tolerate warmer and drier summers, the indirect effects of climate change such as shifts in phenology and an increase in extreme weather events such as storm surges pose the highest long-term threat to the butterfly’s survival outside of habitat loss. Preserving the butterfly’s current habitat and creating more habitat for the butterfly, especially on San Juan Island, should be the first priority of conservation practitioners working with the species.

Type

Text

Keywords

island marble butterfly, conservation, ecology, biogeography, Salish Sea, San Juan Islands

Publisher

Western Washington University

OCLC Number

1531355177

Subject – LCSH

Island marble (Insect)--Habitat--Conservation--Salish Sea Region (B.C. and Wash.); Island marble (Insect)--Climatic factors--Salish Sea Region (B.C. and Wash.); Island marble (Insect)--Effect of habitat modification on--Salish Sea Region (B.C. and Wash.); Island marble (Insect)--Conservation--Salish Sea Region (B.C. and Wash.); Island marble (Insect)--Salish Sea Region (B.C. and Wash.)--Geographical distribution; Island marble (Insect)--Habitat suitability index models--Salish Sea Region (B.C. and Wash.); Endangered species--Conservation--Salish Sea Region (B.C. and Wash.); Prairie conservation--Washington (State)--San Juan Islands; Grassland conservation--Washington (State)--San Juan Islands; Grassland restoration--Washington (State)--San Juan Islands; Habitat conservation--Salish Sea Region (B.C. and Wash.)

Geographic Coverage

Salish Sea (B.C. and Wash.); San Juan Islands (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Rights Statement

http://rightsstatements.org/vocab/InC-NC/1.0/

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.

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