Movement of translocated turtles according to translocation method and habitat structure

Abstract

Dispersal away from the release site is among the main obstacles that reduce translocation success. Scientists should therefore test a variety of translocation methods to reduce dispersal when moving wildlife between sites. The objective of this research was to examine how translocation method (hard-vs. soft-release) and habitat structure (continuous vs. patchy) affect movement of translocated turtles. A hard-release consists of releasing individuals to their new environment without any prior acclimation, whereas a soft-release forces animals to spend time at the release site prior to release. Our results suggest that the most effective translocation technique depends upon habitat structure. A soft-release was effective in minimizing post-release dispersal of translocated turtles in a continuous lotic habitat as there was no difference in the movement of soft-released and resident turtles. However, hard-released turtles undergo extensive movement when translocated to a continuous lotic habitat as hard-released turtles had greater movement than resident turtles. When the release site consists of a patchy wetland complex, a hard-release translocation may be effective as there was no difference in the movement between resident and hard-released turtles. Our study suggests that both the habitat structure of the release site and translocation method play a role in the movement patterns of translocated wildlife. Semi-aquatic turtles or species with poor vagility may make better candidates for hard-release translocations in patchy habitats because these species may be less likely or unable to disperse long distances as result of their behavior, physiology, or the structure of the release site.

Habitat drives dispersal and survival of translocated juvenile desert tortoises

“…We did not find an effect of dispersal on survival, but notably the majority of our animals dispersed small distances from their release. Holding animals in acclimation pens can generally serve to reduce dispersal (Bright & Morris 1994), including for reptiles (Knox & Monks 2014;Attum & Cutshall 2015) and tortoises specifically (Tuberville et al 2005). However, acclimation pens are sometimes ineffective (Nagy et al 2015) and often financially unfeasible.…”

“…Habitat suitability at the recipient site can influence the translocation outcomes via the effects on post-release dispersal, mortality or other causes preventing the establishment of viable populations (Griffith et al 1989;Stamps & Swaisgood 2007;Germano & Bishop 2009;Le Gouar, Mihoub & Sarrazin 2012;Seddon et al 2014;Attum & Cutshall 2015). Forage availability, an often-considered habitat feature, can affect site fidelity and survival after release (Bright & Morris 1994;Cabezas & Moreno 2007).…”

“…Because conservation translocations can contribute to species recovery (Miller, Bell & Germano 2014;Germano et al 2015;Sullivan, Nowak & Kwiatkowski 2015), refinement of translocation protocols is needed to support successful translocations, especially for juvenile tortoises. For chelonians, the structure of the recipient habitat can exert important effects on translocation outcomes (Rittenhouse et al 2008;Nussear et al 2012;Attum & Cutshall 2015), where refuge availability especially can improve the survival (DeGregorio, Buhlmann & Tuberville 2012).…”

“…; Stamps & Swaisgood ; Germano & Bishop ; Le Gouar, Mihoub & Sarrazin ; Seddon et al . ; Attum & Cutshall ). Forage availability, an often‐considered habitat feature, can affect site fidelity and survival after release (Bright & Morris ; Cabezas & Moreno ).…”

A question of scale: Replication and the effective evaluation of conservation interventions

“…Tracking growth, behaviour, or survivorship of headstarts alone, although valuable, cannot inform demographic evaluations (unless the population is a reintroduction and there are no wild turtles besides headstarts), because wild juvenile freshwater turtles experience high mortality compared with adults (Congdon et al 1993). Therefore, the impact of headstart survivorship on a population is only informative in comparison with the survivorship of wild-hatched individuals in the target population, and an experimental approach should be used to compare the fitness of these two groups (Spinks et al 2003;Mitrus 2005;Attum and Cutshall 2015). However, making the comparison presumes that there are wild-hatched juveniles in the population, which may not be the case when natural recruitment is effectively zero (e.g., Ontario Wood Turtle Recovery Team 2010) or when re-establishing populations within a historical range (e.g., Amaral 2007).…”