Waif Gopher Tortoise Survival and Site Fidelity Following Translocation

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. © 2021 The Wildlife Society.     

A large testudinid with African affinities in the post-Messinian (lower Pliocene) record of south-eastern Spain

Herein, we describe Alatochelon myrteum gen. et sp. nov., a large tortoise from the post-Messinian (lower Pliocene) of the area of Puerto de la Cadena (Region of Murcia), Spain. The new taxon cannot be attributed to Titanochelon, which represented the only lineage of large tortoises previously recognized in the Neogene record of Europe. Alatochelon myrteum shows African affinities, especially with the extant African spurred tortoise Centrochelys sulcata. Although close phylogenetic relationships have previously been recognized among some tortoises of both continents, the dispersal of this lineage had always been proposed as having occurred in only one direction: from Europe to Africa. The dispersal of the lineage including the new Spanish form and Centrochelys sulcata from Africa to Europe is proposed here. This proposal is compatible with those previously recognized for some lineages of mammals also found in Puerto de la Cadena, identified as African lineages that probably reached Europe during the Messinian Salinity Crisis event. An African origin is also proposed for the lineage of Titanochelon. Therefore, the two lineages of large derived testudinids (i.e. Geochelona) recognized in the European record experienced diachronic dispersal events from Africa to Europe: that to which Alatochelon belongs probably during the Messinian and the other much earlier, at the beginning of the Miocene or before.     

Sighting frequency and food habits of the leopard tortoise, Geochelone pardalis, in northern Tanzania

Sighting frequency and food habits of the leopard tortoise (Geochelone pardalis) were studied in northern Tanzania from October 1993 to June 1996. Sighting frequency varied significantly between protected (0.22 mhr^?1) and unprotected sites (0.59 mhr^?1), and between Arusha (0.27 mhr^?1) and Serengeti sites (0.56 mhr^?1). The tortoise diet comprised mostly plants (97.8%) and rarely inorganic matter (2.2%). A total of 47 plant species from 21 families was eaten. Forbs made up 74.5% of the plant items and monocots the remainder. Succulents contributed 51.0% of the plant items eaten while grasses and legumes accounted for 16.8% and 13.5%, respectively. Some plant items were eaten more frequently than their occurrence in the habitats.     

The origin of Indian Star tortoises (Geochelone elegans) based on nuclear and mitochondrial DNA analysis: A story of rescue and repatriation

The Indian Star tortoise (Geochelone elegans) belongs to the family Testunidae and is distributed in southwest India and Sri Lanka. In addition to facing loss of its natural habitat, the species is also illegally traded as food and as an exotic pet internationally. Here we report DNA-based analyses for identification and repatriation of these tortoises into their natural habitat. We have attempted to establish the geographical origin of these tortoises rescued from smugglers, by comparing the microsatellite and mitochondrial markers of rescued animals with animals of known provenance. Star tortoises exhibited strong genetic structure in India. The populations from western India were genetically distinct at microsatellite and mitochondrial loci from southern populations. The rescued individuals had similar multilocus genotypes and mitochondrial DNA haplotypes as the reference individuals from south India. However, the precise geographic origin of many of the rescued samples remains unresolved, because we could not assign them to southern populations and the Neighbor-Joining cluster analysis indicated that some of rescued tortoises formed distinct clusters. These data strongly suggest that the rescued group of tortoises is composed of a mix of individuals from differentiated source populations that are probably located in southern India and possibly Sri Lanka. Our study provides valuable information based on molecular markers for the assessment of genetic diversity in Indian Star tortoises.     

Nutrition as a major facet of reptile conservation

The importance of nutrition has not received much recognition in conservation biology. However, captive breeding is possible only if nutritional requirements of animals are met, and effective habitat management requires an evaluation of nutritional resources. Three examples involving reptile conservation are presented. The formulation and testing of experimental meal-type diets proved essential for the large-scale rearing of green iguanas (Iguana iguana) in Panama and Costa Rica, thousands of which have been released into the wild. Survival and growth of captive land iguanas (Conolophus subcristatus) in the Galapagos Islands was markedly improved by development of a complete feed based on locally available ingredients; this was essential to continuation of the conservation program in which juvenile iguanas were repatriated to islands where populations had previously been exterminated. Research on the desert tortoise (Gopherus agassizii) in the Mojave Desert has identified nutritional constraints that may limit utilization of potential food plants. Thus, nutritional status of wild tortoises may depend more on availability of plant species of high nutritional quality than on overall amounts of annual vegetation. Federal and local agencies involved in the conservation and management of tortoise habitat have recognized the need to fund research on tortoise nutrition. We contend that nutrition should be given a central role in conservation programs for reptiles and other animals. (This article is a US Government work and, as such, is in the public domain in the United States of America.) © 1996 Wiley-Liss, Inc.     

Characterization of 20 microsatellite markers in the plowshare tortoise,Astrochelys yniphora

The plowshare tortoise, Astrochelys yniphora, or Angonoka is one of Madagascar’s land tortoises, living in the vicinity of Baly Bay bamboo scrub in northwest Madagascar. Primary threats to this endangered species are due to poaching for pet trade and the loss and fragmentation of its natural habitat. The number of wild Angonoka is estimated to be ~400. Twenty polymorphic nuclear microsatellite loci were isolated from a genomic DNA on individuals from Andrafiafaly in Baly Bay National Park, Madagascar. Results from this study will help for future studies of the social structure and population dynamics of this species as well as identification of confiscated individuals from the illegal pet trade.     

Estimating abundance and population trends when detection is low and highly variable: A comparison of three methods for the Hermann's tortoise

Assessing population trends is a basic prerequisite to carrying out adequate conservation strategies. Selecting an appropriate method to monitor animal populations can be challenging, particularly for low-detection species such as reptiles. This study compares 3 detection-corrected abundance methods (capture–recapture, distance sampling, and N-mixture) used to assess population size of the threatened Hermann's tortoise. We used a single dataset of 432 adult tortoise observations collected at 118 sampling sites in the Plaine des Maures, southeastern France. We also used a dataset of 520 tortoise observations based on radiotelemetry data collected from 10 adult females to estimate and model the availability (g0) needed for distance sampling. We evaluated bias for N-mixture and capture–recapture, by using simulations based on different values of detection probabilities. Finally, we conducted a power analysis to estimate the ability of the 3 methods to detect changes in Hermann's tortoise abundances. The abundance estimations we obtained using distance sampling and N-mixture models were respectively 1.75 and 2.19 times less than those obtained using the capture–recapture method. Our results indicated that g0 was influenced by temperature variations and can differ for the same temperature on different days. Simulations showed that the N-mixture models provide unstable estimations for species with detection probabilities <0.5, whereas capture–recapture estimations were unbiased. Power analysis showed that none of the 3 methods were precise enough to detect slow population changes. We recommend that great care should be taken when implementing monitoring designs for species with large variation in activity rates and low detection probabilities. Although N-mixture models are easy to implement, we would not recommend using them in situations where the detection probability is very low at the risk of providing biased estimates. Among the 3 methods allowing estimation of tortoise abundances, capture–recapture should be preferred to assess population trends. © 2013 The Wildlife Society.     

Seed dispersal by Galápagos tortoises

Aim Large‐bodied vertebrates often have a dramatic role in ecosystem function through herbivory, trampling, seed dispersal and nutrient cycling. The iconic Galápagos tortoises (Chelonoidis nigra) are the largest extant terrestrial ectotherms, yet their ecology is poorly known. Large body size should confer a generalist diet, benign digestive processes and long‐distance ranging ability, rendering giant tortoises adept seed dispersers. We sought to determine the extent of seed dispersal by Galápagos tortoises and their impact on seed germination for selected species, and to assess potential impacts of tortoise dispersal on the vegetation dynamics of the Galápagos. Location Galápagos, Ecuador. Methods To determine the number of seeds dispersed we identified and counted intact seeds from 120 fresh dung piles in both agricultural and national park land. To estimate the distance over which tortoises move seeds we used estimated digesta retention times from captive tortoises as a proxy for retention times of wild tortoises and tortoise movement data obtained from GPS telemetry. We conducted germination trials for five plant species to determine whether tortoise processing influenced germination success. Results In our dung sample, we found intact seeds from > 45 plant species, of which 11 were from introduced species. Tortoises defecated, on average, 464 (SE 95) seeds and 2.8 (SE 0.2) species per dung pile. Seed numbers were dominated by introduced species, particularly in agricultural land. Tortoises frequently moved seeds over long distances; during mean digesta retention times (12 days) tortoises moved an average of 394 m (SE 34) and a maximum of 4355 m over the longest recorded retention time (28 days). We did not find evidence that tortoise ingestion or the presence of dung influenced seed germination success. Main conclusions Galápagos tortoises are prodigious seed dispersers, regularly moving large quantities of seeds over long distances. This may confer important advantages to tortoise‐dispersed species, including transport of seeds away from the parent plants into sites favourable for germination. More extensive research is needed to quantify germination success, recruitment to adulthood and demography of plants under natural conditions, with and without tortoise dispersal, to determine the seed dispersal effectiveness of Galápagos tortoises.     

Population Genetic Assignment of Confiscated Gopher Tortoises

Abstract As gopher tortoises (Gopherus polyphemus) increasingly become threatened throughout their range in Florida, USA, the need for management and conservation will intensify. Here we evaluate the forensic applicability of genetic assignment tests based on microsatellite genotypic data to 1) accurately assign individuals in our genetic database to the sample location or population of origin and 2) determine the origin of 6 confiscated tortoises. Overall, we could correctly assign 90% of the individuals in the database to their population of origin, but we were unable to determine the source of the confiscated tortoises. However, these individuals are unlikely to have come from any of our sampled sites and all 6 may have come from the same population. This approach can be used by law enforcement personnel to identify the origin of confiscated tortoises as well as by developers and wildlife managers to determine the genetic appropriateness of potential recipient populations when it is necessary to relocate individuals.