Relationships between Texas tortoise carapace length, home range size, and habitat selection at sites with invasive grass

Author

Kiley V. Briggs, The University of Texas Rio Grande Valley

Date of Award

5-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dr. Kenneth Pruitt

Second Advisor

Dr. Heather Alexander

Third Advisor

Dr. Karl Berg

Abstract

Invasive grasses in south Texas have the potential to negatively impact the threatened Texas tortoise (Gopherus berlandieri) by reducing the availability of preferred foods (forbs) and may cause tortoises to travel farther, lead to reduced carapace length, and reduce the availability of refugia from heat stress. I used compositional analysis, regression, and ANOVA to explore relationships between invasive grasses and habitat use, home range size, and carapace length, as well as compared daily maximum temperatures between tussocks of an invasive and native grass. Forbs were ranked higher in use over invasive grasses in compositional analysis, but not strongly so (p>0.05), and there was no correlation between home range size and invasive grass or forb cover. Female tortoise carapace length was positively correlated with forb cover (R2=0.106; p=0.005). Temperatures inside invasive grass tussocks were warmer and exceeded the stress point of tortoises more often than in native grass.

Comments

Copyright 2016 Kiley V. Briggs. All Rights Reserved.

https://www.proquest.com/dissertations-theses/relationships-between-texas-tortoise-carapace/docview/1810998788/se-2?accountid=7119

Recommended Citation

Briggs, Kiley V., "Relationships between Texas tortoise carapace length, home range size, and habitat selection at sites with invasive grass" (2016). Theses and Dissertations. 11.
https://scholarworks.utrgv.edu/etd/11