Spatial Use and Survivorship of Translocated Wild‐Caught Texas Horned Lizards

Abstract

The Texas horned lizard (Phrynosoma cornutum), a state threatened species in Texas, USA, appears to be declining throughout much of its distribution. Because of popular interest in restoring lizard populations, we conducted a 3‐year radio‐telemetric study to evaluate the feasibility of reintroducing Texas horned lizards into previously occupied areas with suitable habitat characteristics. We translocated lizards from natural populations in western Texas to the McGillivray and Leona McKie Muse Wildlife Management Area (MWMA) in the Cross Timbers and Prairies of north‐central Texas, an ecoregion that has experienced apparent local extirpations of horned lizards. We translocated lizards after partly restoring a 32.5‐ha portion of the MWMA from ashe juniper (Juniperus ashei)‐honey mesquite (Prosopis glandulosa) woodland to mid‐grass prairie. After a 10‐day acclimation period and soft release, we tracked 57 horned lizards from March 2014 to October 2016 to evaluate daily movements, spatial use, sources of mortality, reproduction, and changes in body condition. Daily movement averages (1.16–174.18 m) and area used by individuals (<0.01–6.81 ha) were similar to those recorded for natural populations, with peaks in movement occurring in May and June. Annual survivorship for individuals (1.1–47.2%) was also similar to that reported from natural populations; however, survivorship declined across the 3 active seasons. Although mortality of translocated lizards was high, body condition remained relatively stable across active seasons, and reproduction occurred each year, indicating that translocation could be a viable option for restoring horned lizard populations to previously occupied parts of their range. © 2019 The Wildlife Society.

Survivorship and Spatial Patterns of an Urban Population of Texas Horned Lizards

“…Preliminary analyses of home range sizes for individuals with >5, >10, and >20 recorded capture events showed no statistical difference in home range size estimation; therefore, we chose to be inclusive in range size estimation by including all individuals with >5 recorded capture events using 95% MCPs (Fig. 4; Miller et al 2020). Average home range areas increased ontogenetically with body size.…”

Soft Release Translocation of Texas Horned Lizards (Phrynosoma cornutum) on an Urban Military Installation in Oklahoma, United States

“…Relatively few published studies have used soft release in conjunction with the translocation of lizard species. However, Miller et al [ 17 ] reported that soft-released adult Texas horned lizards had similar movement and survival rates to those reported in the literature for resident animals. Another study using soft release with jeweled geckos ( Naultinus gemmeus ) reported that soft release reduced post-release dispersal movements [ 15 ].…”

“…Many translocated animals immediately attempt to return to their site of capture, and animals confined in soft release pens often display increased movement around the periphery of the pen for some period of time; it has been suggested that releasing animals from pens after they cease this behavior might be beneficial [ 12 ]. Soft release often allows animals to develop, practice, and display natural behaviors, such as foraging, mating, thermoregulating, and burrowing, and has proven effective for a number of successful translocation projects [ 13 , 14 , 15 , 16 ] including, recently, for the Texas horned lizard ( Phrynosoma cornutum ; [ 17 ]). For example, gopher tortoises ( Gopherus polyphemus ) that were soft-released in South Carolina moved shorter distances and experienced higher survival upon release than individuals that were hard-released [ 13 ].…”

Predation release of Texas horned lizards (Phrynosoma cornutum) living in small towns

“…Texas horned lizards are known to have a multitude of predators including snakes, predatory lizards, birds, rodents, canids, and felids (Sherbrooke, 2003). Their low annual survival rate (8.9%–54%) is also often attributed to high predation pressure (Endriss et al., 2007; Fair & Henke, 1999; Miller et al., 2020).…”