Settlement pattern of tortoises translocated into the wild: a key to evaluate population reinforcement success

Pille, Fabien; Sébastien, Caron; Bonnet, Xavier; Deleuze, Simon; Busson, Delphine; Etien, Thomas; Girard, Florent; Ballouard, Jean-Marie

doi:10.1007/s10531-017-1445-2

Cited by 13 publications

(13 citation statements)

References 70 publications

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“…Reduced rates of apparent survival in the initial 1-2 years have been predominantly attributed to dispersal rather than direct mortality (Tuberville et al 2008), and this behavior is reduced as tortoises acclimate to their new environment and establish home ranges Epperson 2005, Tuberville et al 2005). Similar patterns of acclimation have been reported for other translocated tortoise species, including the Mojave desert tortoise (Gopherus agassizii; Nussear et al 2012, Farnsworth et al 2015) and Hermann's tortoise (Testudo hermanni; Pille et al 2018).…”

supporting

confidence: 76%

Waif Gopher Tortoise Survival and Site Fidelity Following Translocation

et al. 2021

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Gopher tortoises (Gopherus polyphemus) are among the most commonly translocated reptiles. Waif tortoises are animals frequently of unknown origin that have been displaced from the wild and often held in human possession for various reasons and durations. Although there are risks associated with any translocation, waif tortoises are generally excluded from translocation projects because of heightened concerns of introducing pathogens and uncertainty about the post-release survival of these individuals. If these risks could be managed, waif tortoises could have conservation value because they can provide the needed numbers to stabilize populations. In the early 1990s, the discovery of an isolated population of gopher tortoises (≤15 individuals) near Aiken, South Carolina, USA, prioritized establishment of the Aiken Gopher Tortoise Heritage Preserve (AGTHP). Because of the population's need for augmentation and the site's isolation from other tortoise populations, the AGTHP provided the opportunity to evaluate the post-release survival of translocated waif tortoises without compromising a viable population. Since 2006, >260 waif tortoises have been introduced to the preserve. Using a Cormack-Jolly-Seber modeling framework to analyze release records and capture histories from trapping efforts in 2017 and 2018, we estimated the long-term apparent survival and site fidelity of this population composed largely of waif tortoises. We estimated annual apparent survival probabilities to be high (≥0.90) for subadult, adult male, and adult female tortoises, and these rates were similar to those reported for wild-to-wild translocated gopher tortoises and those from unmanipulated populations. Of the tortoises recaptured within the boundaries of the preserve, 75% were located within 400 m of their release location. These results suggest that waif tortoises could be an important resource in reducing the extirpation risk of isolated populations.

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confidence: 76%

Waif Gopher Tortoise Survival and Site Fidelity Following Translocation

et al. 2021

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“…Long‐term analyses of survival of translocated captive gopher and Hermann's tortoises in protected areas was high: ≥0.90 annually for subadult and adult gopher after approximately 12 years (McKee et al 2021) and 0.978 after 14 years and 0.972 after 29 years for Hermann's tortoises (Bertolero et al 2007, 2018). Predators negatively affected success of translocations of gopher and Herman's tortoises (Ashton and Burke 2007, Bertolero et al 2007, Pille et al 2018). Ashton and Burke (2007) predicted that a specific re‐located gopher tortoise population would not remain viable without predator control, and Bertolero et al (2007:366) reported that “…predators (even at very low densities) can jeopardize a reintroduction” and that they significantly decreased survival of translocated tortoises.…”

Section: Discussionmentioning

confidence: 99%

Drivers of survival of translocated tortoises

Mack

Berry

2023

J Wildl Manag

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Translocation of animals, especially for threatened and endangered species, is a currently popular but very challenging activity. We translocated 158 adult Agassiz's desert tortoises (Gopherus agassizii), a threatened species, from the National Training Center, Fort Irwin, in the central Mojave Desert in California, USA, to 4 plots as part of a long‐distance, hard‐release, mitigation‐driven translocation to prevent deaths from planned military maneuvers. We monitored demographic and behavioral variables of tortoises fitted with radio‐transmitters from 2008 to 2018. By the end of the project, 17.72% of tortoises were alive, 65.82% were dead, 15.19% were missing, and 1.27% were removed from the study because they returned to Fort Irwin. Mortality was high during the first 3 years: >50% of the released animals died, primarily from predation. Thereafter, mortality declined but remained high. After 10.5 years, survival was highest, 37.50% (15/40), on the plot closest to original home sites, whereas from 2.56% to 23.68% remained alive on the other 3 release plots. Surviving tortoises settled early, repeatedly using locations where they constructed burrows, compared with tortoises that died or disappeared. Models of behavioral and other variables indicated that numbers of repeatedly used locations (burrows) were a driver of survival throughout the study, although plot location, size and sex of tortoises, and distance traveled were contributors, especially during early years. Because >50% mortality occurred, we considered this translocation unsuccessful. The study area appeared to be an ecological sink with historical and current anthropogenic uses contributing to habitat degradation and a decline in both the resident and released tortoises. Our findings will benefit design and selection of future translocation areas.

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“…Sanitary protocols are needed to handle free-ranging tortoises; nasal and oral secretions, feces, sperm and even urine can be contaminating (Origgi et al, 2012). Similarly, strict protocols are needed during conservation translocations; notably because individuals often travel long distances before settling (Pille et al, 2018), while stress associated with release may promote virus reactivation from latent infection (Griffith, 1993; Martel et al, 2009; Jacobson et al, 2012). Furthermore, captive individuals carrying a wide range of pathogens and parasites represent additional risks to URDT transmission and should be treated specifically (Ahne 1993; Chávarri et al 2012).…”

Section: Discussionmentioning

confidence: 99%

First detection of herpesvirus and prevalence of mycoplasma infection in free-ranging Hermann’s tortoises (Testudo hermanni), and in potential pet vectors

Ballouard¹,

Bonnet

Jourdan³

et al. 2021

Preprint

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Two types of pathogens cause highly contagious upper respiratory tract diseases (URTD) in Chelonians: testudinid herpesviruses (TeHV) and a mycoplasma (Mycoplasma agassizii). In captivity, these infections are frequent and can provoke outbreaks. Pet trade generates international flow of tortoises, often without sanitary checking; individuals intentionally or accidentally released in the wild may spread pathogens. A better understanding of the transmission of infectious agents from captivity to wild tortoises is needed. Many exotic individuals have been introduced in populations of the endangered western Hermann’s tortoise (Testudo hermanni hermanni), notably spur-thighed tortoises (Testudo graeca). We assessed the presence of TeHV and mycoplasma in native western Hermann’s tortoises and in potential pet vectors in south-eastern France. Using a large sample (N=572 tortoises), this study revealed the worrying presence of herpesvirus in 7 free-ranging individuals (3 sub-populations). Additionally, Mycoplasma agassizii was detected in 15 of the 18 populations sampled with a frequency ranging from 2.5 to 25%. Exotic spur-thighed tortoises showed high frequency of Mycoplasma infection in captivity (18%) and in individuals (50%) found in native Hermann’s tortoise sub-populations, suggesting that this species could be a significant vector. The paucity of information of TeHV on European tortoise’ URTD in natural settings, especially in combination with mycoplasma, prompts for further studies. Indeed, sick tortoises remain concealed and may not be easily detected in the field. Our results indicate that both the prevalence and health impact of URTD are high should be scrutinized in the field.

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Settlement pattern of tortoises translocated into the wild: a key to evaluate population reinforcement success

Cited by 13 publications

References 70 publications

Waif Gopher Tortoise Survival and Site Fidelity Following Translocation

Waif Gopher Tortoise Survival and Site Fidelity Following Translocation

Drivers of survival of translocated tortoises

First detection of herpesvirus and prevalence of mycoplasma infection in free-ranging Hermann’s tortoises (Testudo hermanni), and in potential pet vectors

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