Estimating distribution and detection of Kirtland's Snake (Clonophis kirtlandii) to design effective presence/absence surveys

Stewart, Tyler

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https://hdl.handle.net/2142/117824 Copy

Description

Title

Estimating distribution and detection of Kirtland's Snake (Clonophis kirtlandii) to design effective presence/absence surveys

Author(s)

Stewart, Tyler

Issue Date

2022-12-05

Director of Research (if dissertation) or Advisor (if thesis)

• Dreslik, Michael J
• Crawford, John A

Committee Member(s)

• Kuhns, Andrew R
• Ward, Michael P

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Environmental niche model
• Habitat suitability
• Occupancy

Abstract

Anthropogenic disturbances often negatively impact wildlife populations, leading to population declines and local extirpations. To effectively manage imperiled wildlife populations, it is vital to know their current distribution so critical habitat can be targeted for conservation. Presence/absence surveys provide a means for assessing the status of wildlife in potentially suitable habitat. However, time and funding constraints limit the number of sites that can be surveyed. The time and funding needed for presence/absence surveys are further compounded by rare and cryptic species, which require large survey efforts to detect. I developed a framework for designing presence/absence surveys for the cryptic Kirtland's Snake (Clonophis kirtlandii) in Illinois while optimizing survey resources. In Illinois, nearly all the Kirtland's Snake primary habitat, wet prairie, has been lost to agricultural development. Consequently, Kirtland's Snake has been listed as a threatened species in Illinois, although knowledge of current distributions is limited due to low detection probabilities. I created a Species Distribution Model (SDM) for Kirtland's Snake in Illinois and classified regions based on environmental suitability. I cross-referenced the SDM with existing protected lands in Illinois and targeted >2,500 sites for future surveys. I estimated the amount of effort needed to detect populations at sites by estimating detection probabilities of three known Kirtland's Snake populations. High cloud cover, moderate air temperature, and low relative humidity were found to enhance the detection probability of Kirtland's Snakes and from the middle of May to the beginning of July was the best time to conduct surveys. I created a spreadsheet tool for surveyors to estimate detection probabilities and the number of surveys needed to assume absence under varying survey-specific environmental and temporal conditions. Finally, I provided survey design recommendations to optimize the time and funding needed to assess potential Kirtland's Snake habitat.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Tyler Stewart

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