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

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\u3e0.05), 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