Does translocation influence physiological stress in the desert tortoise?

Abstract

Wildlife translocation is increasingly used to mitigate disturbances to animals or habitat due to human activities, yet little is known about the extent to which translocating animals causes stress. To understand the relationship between physiological stress and translocation, we conducted a multiyear study (2007)(2008)(2009) using a population of desert tortoises (Gopherus agassizii) near Fort Irwin, California. Blood samples were collected from adult tortoises in three treatment groups (resident, translocated and control) for 1 year prior to and 2 years after translocation. Samples were analyzed by radioimmunoassay for plasma total corticosterone (CORT), a glucocorticoid hormone commonly associated with stress responses in reptiles. CORT values were analyzed in relation to potential covariates (animal sex, date, behavior, treatment, handling time, air temperature, home-range size, precipitation and annual plant production) among seasons and years. CORT values in males were higher than in females, and values for both varied monthly throughout the activity season and among years. Year and sex were strong predictors of CORT, and translocation explained little in terms of CORT. Based on these results, we conclude that translocation does not elicit a physiological stress response in desert tortoises. bs_bs_banner Animal Conservation. Print ISSN 1367-9430 Physiological stress and translocation in tortoises K. K. Drake et al.

Mitigation-driven translocation effects on temperature, condition, growth, and mortality of Mojave desert tortoise ( Gopherus agassizii ) in the face of solar energy development

“…For short-distance translocations, we observed short-term thermal effects primarily in the first month but no differences in condition, growth or mortality for translocated tortoises. Several authors have suggested translocation of desert tortoises may serve as a conservation or mitigation tool (Drake et al, 2012;Field et al, 2007;Nussear et al, 2012), and given the lack of group effects on condition, growth, or mortality, our study supports these previous findings.…”

“…These studies have found no effect of translocation compared with resident or control populations on survivorship or mortality (Esque et al, 2010;Field et al, 2007;Nussear et al, 2012), stress (Drake et al, 2012), or reproductive output . Increased movement has been the largest effect observed in both long-distance (Field et al, 2007;Nussear et al, 2012) and short-distance (Farnsworth et al, 2015;Hinderle et al, 2015) translocations.…”

“…A few studies have addressed the effects of translocation on this threatened reptile (Drake et al, 2012;Esque et al, 2010;Field et al, 2007;Hinderle et al, 2015;Nussear et al, 2012), but only one has addressed mitigation-driven translocation effects on desert tortoises following utility-scale solar development (Farnsworth et al, 2015). Prior studies indicated tortoise movements increased initially post-translocation, after which tortoises established home ranges, movement behavior, or space-use indistinguishable from control tortoises (Farnsworth et al, 2015;Field et al, 2007;Nussear et al, 2012).…”

Sex-specific ecophysiological responses to environmental fluctuations of free-ranging Hermann's tortoises: implication for conservation

“…Punctures were performed in the field before 12.00 h to limit the influence of daily variation. Samples were collected within 5 min to limit the impact of handling stress (Jessop et al ., 2003; Drake et al ., 2012; Bonnet et al ., 2016a). Between 0.5 and 1.0 ml of blood was retrieved from the dorsal subcarapacial cervical plexus with a 25 or 26 gauge needle connected to a 1 ml syringe and transferred in a lithium heparinized tube.…”

“…Monitoring GC concentrations of individuals in different habitats represents a means to identify environmental stressors (Drake et al ., 2012). Nonetheless, gathering CG concentrations in isolation is poorly informative because contrasted GC concentration profiles do not necessarily translate into contrasting demographic response.…”