Assessment of a freshwater turtle reintroduction

Kessler, Ethan Jonathan

Permalink

https://hdl.handle.net/2142/108115 Copy

Description

Title

Assessment of a freshwater turtle reintroduction

Author(s)

Kessler, Ethan Jonathan

Issue Date

2020-04-21

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

Dreslik, Michael J.

Doctoral Committee Chair(s)

Schooley, Robert L.

Committee Member(s)

• Ward, Michael P.
• Phillips, Christopher A.

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Reintroduction
• Translocation
• Headstarting
• Turtle
• Conservation
• Integral Projection Model
• Structured Population Model
• Macrochelys temminckii

Abstract

The history of conservation translocations goes back over a century, but reintroduction biology is a young discipline. Reintroductions often elicit criticism for attempting to restore populations without directly addressing sources of declines. However, global population declines have made reintroduction a necessary tool for modern conservation necessitating the refinement of reintroduction methodologies. I evaluated behavior, health, and demography of a reintroduced population of Alligator Snapping Turtles (Macrochelys temminckii) with reference to the suitability of this species for reintroduction and the prognosis of the reintroduction. Using radio telemetry, I found dispersal was size-dependent, but turtles displayed no maladaptive post-release dispersal behavior. Larger turtles were more likely to move and moved farther distances than smaller turtles. Movement behavior was related positively to temperature and precipitation. However, further analysis showed precipitation resulted in passive downstream dispersal, which could become exacerbated with predicted increases in flooding due to climate change. Habitat use and selection of reintroduced turtles were similar to natural populations of M. temminckii. Because turtles preferred higher canopy cover and log jams, managers should consider them when managing habitat or choosing release sites. I found smaller turtles selected shallow water, whereas larger turtles selected for deeper water. Thus, providing heterogeneous habitats should be a management goal for this species due to ontogenetic shifts in habitat requirements. Hematologic assessments of reintroduced turtles pre- and post-release identified non-health drivers of these values. I found packed cell volume (PCV) and white blood cell counts (WBC) varied by size and season, while total solids (TS) measures were unique to sampling periods. My results show that population-specific baselines that consider environmental and individual variation are important for maximizing the utility of hematologic assessments. Finally, I constructed integral projection models (IPMs) using population-specific survival and individual growth rates. The reintroduced population was declining (λ = 0.95), although improving individual growth and adult survival through a reduction of incidental bycatch resulted in a stable population. Elasticity analysis further illustrated the value of individual growth and survival for population growth. Ultimately, though M. temminckii appears well-suited for reintroduction, low site-specific individual growth rates and incidental bycatch resulted in a low probability of success for the current reintroduction.

Graduation Semester

2020-05

Type of Resource

Thesis

Permalink

http://hdl.handle.net/2142/108115

Copyright and License Information

Copyright 2020 Ethan J. Kessler

Owning Collections