Optimizing survey design for shasta salamanders (Hydromantes spp.) to estimate occurrence in little-studied portions of their range

Journal of Herpetology
By: , and 

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Abstract

Shasta salamanders (collectively, Hydromantes samweli, H. shastae, and H. wintu; hereafter, Shasta salamander) are endemic to northern California in the general vicinity of Shasta Lake reservoir. Although generally associated with limestone, they have repeatedly been found in association with other habitats, calling into question the distribution of the species complex. Further limiting our knowledge of the species' distributions is that they are only active or available for sampling on the soil surface for a small portion of the year, and detection probabilities for the species have never been estimated. We developed and implemented a survey protocol designed to estimate detection, availability, and occurrence probabilities from December 2019 through March 2020. We provide inference on Shasta salamander occurrence in portions of their range that have received little survey effort. We found that Shasta salamander occurrence was positively associated with the percent cover of embedded rock, and the species' availability (i.e., probability of being active on the soil surface during sampling) was positively related to relative humidity. The probability of occurrence of Shasta salamanders in our study area was low, and our winter-to-spring survey protocol was effective for estimating detection, availability, and occurrence probabilities in the study area and at specific sites. We suggest that conducting replicate surveys that quantify animal availability and detection probabilities will facilitate a better understanding of the habitat associations of Shasta salamanders and other rare species that might often be unavailable for detection.

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Publication type Article
Publication Subtype Journal Article
Title Optimizing survey design for shasta salamanders (Hydromantes spp.) to estimate occurrence in little-studied portions of their range
Series title Journal of Herpetology
DOI 10.1670/20-119
Volume 56
Issue 2
Year Published 2022
Language English
Publisher BioOne
Contributing office(s) Patuxent Wildlife Research Center, Western Ecological Research Center
Description 11 p.
First page 218
Last page 228
Country United States
State California
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