A species distribution model for guiding Oregon spotted frog (Rana pretiosa) surveys near the southern extent of its geographic range

Graduation Date

2011

Document Type

Thesis

Program

Other

Program

Thesis (M.A.)--Humboldt State University, Biological Sciences, 2011

Committee Chair Name

Sharyn Marks

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Maximum entropy, Humboldt State University -- Theses -- Biology, Rana pretiosa, Maxent, Frog, Amphibians, Modeling, Oregon spotted frog, Species distribution modeling

Abstract

The Oregon spotted frog (Rana pretiosa), endemic to the Pacific Northwest, was once considered widespread in complex, warm water wetlands. Over 70% of historic populations are thought to be extirpated with range-wide habitat loss exceeding 90%. Using Maxent, I developed a series of Species Distribution Models (SDMs) to identify suitable habitat and predict the distribution of Rana pretiosa toward the southern extent of its geographic range. These SDMs were generated from two sets of spatial data: a set of occurrence points and a suite of environmental variables. Occurrence data included all verified populations within the study area. Environmental variables, used to characterize habitat associated with recognized populations, included variables derived from climatic, topographic, land cover and soil datasets. Three unique SDMs were averaged to produce a single distribution map that predicts and ranks suitable habitat across the species' southern range. I used the averaged output from the SDMs, along with aerial, topographic and National Wetlands Inventory imagery, to identify optimal survey sites within the Klamath and Pit river hydrographic basins. I surveyed 18 sites repeatedly and investigated an additional 44 sites. I attempted to focus my efforts on private land, as most preceding surveys in this region were conducted on public land. While I did not detect Rana pretiosa in California, I documented two individuals at a previously unrecognized site in Klamath County, Oregon. This detection is significant because it represents the species' most northern point of occurrence in the Wood River and because only eight extant populations are currently recognized within the Klamath River hydrographic basin.

https://scholarworks.calstate.edu/concern/theses/6h440v88h

Share

 
COinS