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.     

Lineage Identification and Genealogical Relationships Among Captive Galápagos Tortoises

Genetic tools have become a critical complement to traditional approaches for meeting short‐ and long‐term goals of ex situ conservation programs. The San Diego Zoo (SDZ) harbors a collection of wild‐born and captive‐born Galápagos giant tortoises (n = 22) of uncertain species designation and unknown genealogical relationships. Here, we used mitochondrial DNA haplotypic data and nuclear microsatellite genotypic data to identify the evolutionary lineage of wild‐born and captive‐born tortoises of unknown ancestry, to infer levels of relatedness among founders and captive‐born tortoises, and assess putative pedigree relationships assigned by the SDZ studbook. Assignment tests revealed that 12 wild‐born and five captive‐born tortoises represent five different species from Isabela Island and one species from Santa Cruz Island, only five of which were consistent with current studbook designations. Three wild‐born and one captive‐born tortoise were of mixed ancestry. In addition, kinship analyses revealed two significant first‐order relationship pairs between wild‐born and captive‐born tortoises, four second‐order relationships (half‐sibling) between wild‐born and captive tortoises (full‐sibs or parent‐offspring), and one second‐order relationship between two captive‐born tortoises. Of particular note, we also reconstructed a first‐order relationship between two wild‐born individuals, violating the founder assumption. Overall, our results contribute to a worldwide effort in identifying genetically important Galápagos tortoises currently in captivity while revealing closely related founders, reconstructing genealogical relationships, and providing detailed management recommendations for the SDZ tortoises. Zoo Biol 31:107;–120, 2012. © 2011 Wiley Periodicals, Inc.     

Persistence of distinctive morphotypes in the native range of the CITES‐listed Aldabra giant tortoise

Understanding the extent of morphological variation in the wild population of Aldabra giant tortoises is important for conservation, as morphological variation in captive populations has been interpreted as evidence for lingering genes from extinct tortoise lineages. If true, this could impact reintroduction programmes in the region. The population of giant tortoises on Aldabra Atoll is subdivided and distributed around several islands. Although pronounced morphological variation was recorded in the late 1960s, it was thought to be a temporary phenomenon. Early researchers also raised concerns over the future of the population, which was perceived to have exceeded its carrying capacity. We analyzed monthly monitoring data from 12 transects spanning a recent 15‐year period (1998–2012) during which animals from four subpopulations were counted, measured, and sexed. In addition, we analyzed survival data from individuals first tagged during the early 1970s. The population is stable with no sign of significant decline. Subpopulations differ in density, but these differences are mostly due to differences in the prevailing vegetation type. However, subpopulations differ greatly in both the size of animals and the degree of sexual dimorphism. Comparisons with historical data reveal that phenotypic differences among the subpopulations of tortoises on Aldabra have been apparent for the last 50 years with no sign of diminishing. We conclude that the giant tortoise population on Aldabra is subject to varying ecological selection pressures, giving rise to stable morphotypes in discrete subpopulations. We suggest therefore that (1) the presence of morphological differences among captive Aldabra tortoises does not alone provide convincing evidence of genes from other extinct species; and (2) Aldabra serves as an important example of how conservation and management in situ can add to the scientific value of populations and perhaps enable them to better adapt to future ecological pressures.     

Are captive tortoises a reservoir for conservation? An assessment of genealogical affiliation of captive Gopherus agassizii to local, wild populations

The conservation of tortoises poses a unique situation because several threatened species are commonly kept as pets within their native ranges. Thus, there is potential for captive populations to be a reservoir for repatriation efforts. We assess the utility of captive populations of the threatened Agassiz’s desert tortoise (Gopherus agassizii) for recovery efforts based on genetic affinity to local areas. We collected samples from 130 captive desert tortoises from three desert communities: two in California (Ridgecrest and Joshua Tree) and the Desert Tortoise Conservation Center (Las Vegas) in Nevada. We tested all samples for 25 short tandem repeats and sequenced 1,109 bp of the mitochondrial genome. We compared captive genotypes to a database of 1,258 Gopherus samples, including 657 wild caught G. agassizii spanning the full range of the species. We conducted population assignment tests to determine the genetic origins of the captive individuals. For our total sample set, only 44 % of captive individuals were assigned to local populations based on genetic units derived from the reference database. One individual from Joshua Tree, California, was identified as being a Morafka’s desert tortoise, G. morafkai, a cryptic species which is not native to the Mojave Desert. Our data suggest that captive desert tortoises kept within the native range of G. agassizii cannot be presumed to have a genealogical affiliation to wild tortoises in their geographic proximity. Precautions should be taken before considering the release of captive tortoises into the wild as a management tool for recovery.     

Tracing Genetic Lineages of Captive Desert Tortoises in Arizona

Abstract: We genotyped 180 captive desert tortoises (Gopherus agassizii) from Kingman (n = 45), Phoenix (n = 113), and Tucson (n = 22), Arizona, USA, to determine if the genetic lineage of captives is associated with that of wild tortoises in the local area (Sonoran Desert). We tested all samples for 16 short tandem repeats and sequenced 1,109 base pairs of mitochondrial DNA (mtDNA). To determine genetic origin, we performed assignment tests against a reference database of 997 desert tortoise samples collected throughout the Mojave and Sonoran Deserts. We found that >40% of our Arizona captive samples were genetically of Mojave Desert or hybrid origin, with the percentage of individuals exhibiting the Mojave genotype increasing as the sample locations approached the California, USA, border. In Phoenix, 11.5% were Sonoran–Mojave crosses, and 8.8% were hybrids between desert tortoise and Texas tortoise (G. berlandieri). Our findings present many potential implications for wild tortoises in the Sonoran Desert of Arizona. Escaped or released captive tortoises with Mojave or hybrid genotypes have the potential to affect the genetic composition of Sonoran wild populations. Genotyping captive desert tortoises could be used to inform the adoption process, and thereby provide additional protection to native desert-tortoise populations in Arizona.     

Densities of Ecological Replacement Herbivores Required to Restore Plant Communities: A Case Study of Giant Tortoises on Pinta Island,Galápagos

Loss of native herbivores and introduction of livestock in many arid and semi‐arid ecosystems around the world has shifted the competitive balance from herbaceous to woody plants, leading to biodiversity loss, reduced plant productivity, and soil erosion. To restore functions of these ecosystems, ecological replacements have been proposed as substitutes for extinct native herbivores. Here we predict how an ecological replacement giant tortoise population (Chelonoidis spp.) would interact with woody plants on Pinta Island in the Galápagos Archipelago, where a small group of replacement tortoises was introduced in 2010 to initiate restoration of the island's plant community. We developed an individual‐based, spatially explicit simulation model that incorporated field‐derived tortoise behavior and tortoise–plant interaction data to test whether tortoise introductions could lead to broad‐scale changes in the plant community and, if so, at what tortoise densities. Tortoises reduced vegetation density in most (81%) 50‐year‐long simulations if the tortoise density was at least 0.7 per hectare, a value well below typical densities. In a smaller proportion of simulations (30%), tortoises increased local vegetation patchiness. Our results suggest that even moderate‐density tortoise populations can reverse woody plant encroachment. Deployment of ecological replacement giant tortoises may therefore be a viable approach for restoring other arid and semi‐arid ecosystems where a native herbivore that previously had strong interactions with the plant community has gone extinct .     

Biogeography of Parasitic Nematode Communities in the Galápagos Giant Tortoise: Implications for Conservation Management

The Galápagos giant tortoise is an icon of the unique, endemic biodiversity of Galápagos, but little is known of its parasitic fauna. We assessed the diversity of parasitic nematode communities and their spatial distributions within four wild tortoise populations comprising three species across three Galápagos islands, and consider their implication for Galápagos tortoise conservation programmes. Coprological examinations revealed nematode eggs to be common, with more than 80% of tortoises infected within each wild population. Faecal samples from tortoises within captive breeding centres on Santa Cruz, Isabela and San Cristobal islands also were examined. Five different nematode egg types were identified: oxyuroid, ascarid, trichurid and two types of strongyle. Sequencing of the 18S small-subunit ribosomal RNA gene from adult nematodes passed with faeces identified novel sequences indicative of rhabditid and ascaridid species. In the wild, the composition of nematode communities varied according to tortoise species, which co-varied with island, but nematode diversity and abundance were reduced or altered in captive-reared animals. Evolutionary and ecological factors are likely responsible for the variation in nematode distributions in the wild. This possible species/island-parasite co-evolution has not been considered previously for Galápagos tortoises. We recommend that conservation efforts, such as the current Galápagos tortoise captive breeding/rearing and release programme, be managed with respect to parasite biogeography and host-parasite co-evolutionary processes in addition to the biogeography of the host.     

Demographic Outcomes and Ecosystem Implications of Giant Tortoise Reintroduction to Espa?ola Island,Galapagos

Restoration of extirpated species via captive breeding has typically relied on population viability as the primary criterion for evaluating success. This criterion is inadequate when species reintroduction is undertaken to restore ecological functions and interactions. Herein we report on the demographic and ecological outcomes of a five-decade-long population restoration program for a critically endangered species of “ecosystem engineer”: the endemic Española giant Galapagos tortoise (Chelonoidis hoodensis). Our analysis of complementary datasets on tortoise demography and movement, tortoise-plant interactions and Española Island’s vegetation history indicated that the repatriated tortoise population is secure from a strictly demographic perspective: about half of tortoises released on the island since 1975 were still alive in 2007, in situ reproduction is now significant, and future extinction risk is low with or without continued repatriation. Declining survival rates, somatic growth rates, and body condition of repatriates suggests, however, that resources for continued population growth are increasingly limited. Soil stable carbon isotope analyses indicated a pronounced shift toward woody plants in the recent history of the island’s plant community, likely a legacy of changes in competitive relations between woody and herbaceous plants induced by now-eradicated feral goats and prolonged absence of tortoises. Woody plants are of concern because they block tortoise movement and hinder recruitment of cactus–a critical resource for tortoises. Tortoises restrict themselves to remnant cactus patches and areas of low woody plant density in the center of the island despite an apparent capacity to colonize a far greater range, likely because of a lack of cactus elsewhere on the island. We conclude that ecosystem-level criteria for success of species reintroduction efforts take much longer to achieve than population-level criteria; moreover, reinstatement of endangered species as fully functioning ecosystem engineers may often require large-scale habitat restoration efforts in concert with population restoration.     

Structure and projected decline of a Karoo dwarf tortoise population

Inconspicuous, secretive, or sparsely distributed species receive relatively little research attention, potentially leading to uncertainty about their status and lack of efforts to conserve them. Karoo dwarf tortoises (Chersobius boulengeri) are endemic to South Africa, spend most of the time in retreats at remote arid locations, and are seldom seen. We conducted a 3-year (2018–2020) mark-recapture study to investigate the size and structure of the only Karoo dwarf tortoise population currently known to exist. The population in the 16-ha core of our study site consisted primarily of adult males and females, at a density of 3.3 individuals/ha. Many individuals had severely worn shells and appeared old. Small individuals (straight carapace length <65 mm) represented just 8% of the population and were mostly recent hatchlings. Overall, tortoises had high estimated survival rates (0.77–0.95; lower 95% confidence limit for the smallest tortoises was 0.16), despite a 15-month drought. The lack of small individuals may reflect low levels of recruitment and population decline. Predation by corvids was an obvious threat to all size classes. We estimated that the local population across the 250-ha study area was 800–900 males and females, and recommend precautionary conservation measures focused on reducing human-subsidized avian predation.     

Intestinal Cryptosporidium sp. infection in the Egyptian tortoise, Testudo kleinmanni

An adult Egyptian tortoise (Testudo kleinmanni) presented with clinical signs of enteritis and died 5 weeks after initiation of antibiotic therapy. Histological examination of the small intestine revealed heavy infection with Cryptosporidium sp.; over 80% of epithelial cells harboured the pathogen. No Cryptosporidium developmental stages were present in the stomach or the lungs. The intestinal lamina propria and mucosa were infiltrated by heterophils, lymphocytes and macrophages. The present study constitutes the first report of Cryptosporidium sp. infection in T. kleinmanni, and the first histological documentation of intestinal cryptosporidiosis in Chelonia.     

The Dominance of Introduced Plant Species in the Diets of Migratory Galapagos Tortoises Increases with Elevation on a Human‐Occupied Island

The distribution of resources and food selection are fundamental to the ecology, life history, physiology, population dynamics, and conservation of animals. Introduced plants are changing foraging dynamics of herbivores in many ecosystems often with unknown consequences. Galapagos tortoises, like many herbivores, undertake migrations along elevation gradients driven by variability in vegetation productivity which take them into upland areas dominated by introduced plants. We sought to characterize diet composition of two species of Galapagos tortoises, focussing on how the role of introduced forage species changes over space and the implications for tortoise conservation. We quantified the distribution of tortoises with elevation using GPS telemetry. Along the elevation gradient, we quantified the abundance of introduced and native plant species, estimated diet composition by recording foods consumed by tortoises, and assessed tortoise physical condition from body weights and blood parameter values. Tortoises ranged between 0 and 429 m in elevation over which they consumed at least 64 plant species from 26 families, 44 percent of which were introduced species. Cover of introduced species and the proportion of introduced species in tortoise diets increased with elevation. Introduced species were positively selected for by tortoises at all elevations. Tortoise physical condition was either consistent or increased with elevation at the least biologically productive season on Galapagos. Santa Cruz tortoises are generalist herbivores that have adapted their feeding behavior to consume many introduced plant species that has likely made a positive contribution to tortoise nutrition. Some transformed habitats that contain an abundance of introduced forage species are compatible with tortoise conservation.     

Serologic and molecular evidence for Testudinid herpesvirus 2 infection in wild Agassiz's desert tortoises, Gopherus agassizii

Following field observations of wild Agassiz's desert tortoises (Gopherus agassizii) with oral lesions similar to those seen in captive tortoises with herpesvirus infection, we measured the prevalence of antibodies to Testudinid herpesvirus (TeHV) 3 in wild populations of desert tortoises in California. The survey revealed 30.9% antibody prevalence. In 2009 and 2010, two wild adult male desert tortoises, with gross lesions consistent with trauma and puncture wounds, respectively, were necropsied. Tortoise 1 was from the central Mojave Desert and tortoise 2 was from the northeastern Mojave Desert. We extracted DNA from the tongue of tortoise 1 and from the tongue and nasal mucosa of tortoise 2. Sequencing of polymerase chain reaction products of the herpesviral DNA-dependent DNA polymerase gene and the UL39 gene respectively showed 100% nucleotide identity with TeHV2, which was previously detected in an ill captive desert tortoise in California. Although several cases of herpesvirus infection have been described in captive desert tortoises, our findings represent the first conclusive molecular evidence of TeHV2 infection in wild desert tortoises. The serologic findings support cross-reactivity between TeHV2 and TeHV3. Further studies to determine the ecology, prevalence, and clinical significance of this virus in tortoise populations are needed.     

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.     

Mycoplasma and herpesvirus PCR detection in tortoises with rhinitis-stomatitis complex in Spain

Chelonid herpesvirus (ChHV) and mycoplasmal infections cause similar clinical signs in terrestrial tortoises and may be the most important causative agents of rhinitis-stomatitis complex, a common disease in captive tortoises worldwide. Currently, diagnosis of ChHV and Mycoplasma spp. infections is most often based on serologic testing. However, serologic results only detect past exposure, and the specificity of these tests can be reduced due to antigenic cross-reactions with other pathogens. Molecular-based techniques could help to define the causative agent and to better manage infected tortoises. Using polymerase chain reaction, we analyzed 63 tortoises (59 spur-thighed tortoise, Testudo graeca; three Greek tortoise, Testudo ibera; and one Russian tortoise, Agryonemys horsfieldii) with clinical signs of rhinitis-stomatitis complex to identify the causative agent. Molecular evidence of ChHV type I (24%), type II (3%), and Mycoplasma agassizii (6%) infections, as well as coinfection of Mycoplasma-ChHV and both types of ChHV, were detected. Both ChHV and M. agassizii are considered pathogenic in captive tortoises and both are a threat to wild populations. However, neither agent was detected from most of the symptomatic tortoises we evaluated, indicating that other agents could be involved in the rhinitis-stomatitis complex.     

Genetic variability,management, and conservation implications of the critically endangered Brazilian pitviper Bothrops insularis

Information on demographic, genetic, and environmental parameters of wild and captive animal populations has proven to be crucial to conservation programs and strategies. Genetic approaches in conservation programs of Brazilian snakes remain scarce despite their importance for critically endangered species, such as Bothrops insularis, the golden lancehead, which is endemic to Ilha da Queimada Grande, coast of São Paulo State, Brazil. This study aims to (a) characterize the genetic diversity of ex situ and in situ populations of B. insularis using heterologous microsatellites; (b) investigate genetic structure among and within these populations; and (c) provide data for the conservation program of the species. Twelve informative microsatellites obtained from three species of the B. neuwiedi group were used to access genetic diversity indexes of ex situ and in situ populations. Low‐to‐medium genetic diversity parameters were found. Both populations showed low—albeit significant—values of system of mating inbreeding coefficient, whereas only the in situ population showed a significant value of pedigree inbreeding coefficient. Significant values of genetic differentiation indexes suggest a small differentiation between the two populations. Discriminant analysis of principal components (DAPC) recovered five clusters. No geographic relationship was found in the island, suggesting the occurrence of gene flow. Also, our data allowed the establishment of six preferential breeding couples, aiming to minimize inbreeding and elucidate uncertain parental relationships in the captive population. In a conservation perspective, continuous monitoring of both populations is demanded: it involves the incorporation of new individuals from the island into the captive population to avoid inbreeding and to achieve the recommended allelic similarity between the two populations. At last, we recommend that the genetic data support researches as a base to maintain a viable and healthy captive population, highly genetically similar to the in situ one, which is crucial for considering a reintroduction process into the island.     

Lineage identification of Galápagos tortoises in captivity worldwide

Ex situ conservation strategies may be substantially informed by genetic data, and yet only recently have such approaches been used to facilitate captive population management of endangered species. The Galápagos tortoise Geochelone nigra is an endangered species that has benefited greatly from the application of molecular and population genetic data, but remains vulnerable throughout its range. The geographic and evolutionary origins of 98 tortoises in private collections and zoos on three continents were identified using mitochondrial DNA (mtDNA) control region sequences and multi-locus microsatellite genotype data relative to a large database of representative samplings from all extant populations, including historical population allele frequency data for the Geochelone nigra abingdoni taxon on Pinta by way of museum specimens. All but six individuals had mtDNA haplotypes previously sampled, with the novel haplotypes identified as most closely related to robust populations on the islands of Santa Cruz and Isabela. Multi-locus genotypic assignments corroborated the results obtained from the mtDNA analyses, with 83.7% of individuals consistently assigned to the same locality by both datasets. Overall, the majority of captive unknowns sampled were assigned to the La Caseta Geochelone nigra porteri population, with no fewer than six individuals of hybrid origin detected. Although a purported Pinta individual was revealed to be of Pinzón ancestry, the two females currently housed with Lonesome George exhibited haplotypic and genotypic signatures that indicate that they are among the most appropriate matches for captive breeding. More generally, molecular approaches continue to represent important tools for assessing conservation value, minimizing hybridization and guiding management programs for preserving the distinctiveness of G. nigra taxa in captivity.     

Implications from Monitoring Gopher Tortoises at Two Spatial Scales

Conservation biologists need to effectively monitor species given resource limitations and the inherent challenges of assessing long-term demographic processes. We assessed gopher tortoise (Gopherus polyphemus) abundance at a landscape scale and at the scale of 3 local populations within the Conecuh National Forest (CNF), Alabama, USA, between 1991 and 2017. We collected landscape-level data from line transect distance sampling arranged uniformly across the CNF during a single season (2011); we obtained data for local populations from long-term mark-recapture of individuals at 3 sites selected based on prior knowledge of high density at each. At a landscape scale, we estimated 5,242 (95% CI = 3,538–7,768) tortoises occurred across the approximately 34,000-ha forest, yielding a density of 0.14–0.32 tortoises/ha. These low densities across the landscape suggest that, on average, management activities across the property have not allowed tortoise populations to retain the social structure needed for long-term persistence. The 3 local populations, however, contained 25–60 individuals and densities of 1.9–6.9 tortoises/ha. Over the study period, populations at 2 sites were stable and the third experienced significant population growth. Mean annual survival of individuals was 0.89 and invariant across size classes. Overall, line transect distance sampling is important for assessing landscape-scale abundance of tortoises but may fail to detect local clusters of high-density sites important for population persistence. Our mark-recapture efforts at the local scale revealed that small populations on these high-density sites can exhibit long-term stability or growth even though they do not meet current established criteria for viability. Improved models that incorporate immigration and emigration and better reflect the dynamics of peripheral populations would assist in determining how such populations best contribute to species recovery and regional conservation targets. © 2020 The Wildlife Society.     

Body size development of captive and free‐ranging Leopard tortoises (Geochelone pardalis)

The growth and weight development of Leopard tortoise hatchings (Geochelone pardalis) kept at the Al Wabra Wildlife Preservation (AWWP), Qatar, was observed for more than four years, and compared to data in literature for free‐ranging animals on body weight or carapace measurements. The results document a distinctively faster growth in the captive animals. Indications for the same phenomenon in other tortoise species (Galapagos giant tortoises, G. nigra; Spur‐thighed tortoises, Testudo graeca; Desert tortoises, Gopherus agassizi) were found in the literature. The cause of the high growth rate most likely is the constant provision with highly digestible food of low fiber content. Increased growth rates are suspected to have negative consequences such as obesity, high mortality, gastrointestinal illnesses, renal diseases, “pyramiding,” fibrous osteodystrophy or metabolic bone disease. The apparently widespread occurrence of high growth rates in intensively managed tortoises underlines how easily ectothermic animals can be oversupplemented with nutrients. Zoo Biol 29:517–525, 2010. © 2009 Wiley‐Liss, Inc.     

Changes in the status of tortoise populations in Greece 1984–2001

Three species of tortoise (Testudinidae) occur in Greece (Testudo hermanni, T. graeca and the endemic T. marginata), all of which have been listed as rare or vulnerable. This paper describes the current situation of 75 populations that were last observed in the 1970s and 1980s and described in 1989. Twenty-nine populations had declined in density and/or status (significantly more than had improved), 10 of which were functionally extinct. A particularly notable loss was a dense population of T. marginata at Gytheion in the Peloponnese due to a widespread fire. Declining populations were significantly associated with identified high threat in 1989 and with close proximity to human settlement. There were no significant effects of tortoise species, area of site, characteristics of surrounding areas or original density on these changes. Declines were less associated with agriculture than predicted in 1989, reflecting changing economic conditions in Greece in the 1990s. Continuing threats to tortoise habitats make their long-term future appear bleak outside of protected areas. The risk of extinction from stochastic variation in small populations was also assessed, using the VORTEX program. This risk was much lower than that from habitat loss; 60–96% of populations of 100 tortoises would survive for 1000 years, depending on adult body size, compared to only 0–0.02% of habitats. The high survival potential of small populations would facilitate conservation of the high intraspecific diversity of tortoises in Greece.     

Discriminating patterns and drivers of multiscale movement in herpetofauna: The dynamic and changing environment of the Mojave desert tortoise

Changes to animal movement in response to human‐induced changes to the environment are of growing concern in conservation. Most research on this problem has focused on terrestrial endotherms, but changes to herpetofaunal movement are also of concern given their limited dispersal abilities and specialized thermophysiological requirements. Animals in the desert region of the southwestern United States are faced with environmental alterations driven by development (e.g., solar energy facilities) and climate change. Here, we study the movement ecology of a desert species of conservation concern, the Mojave desert tortoise (Gopherus agassizii). We collected weekly encounter locations of marked desert tortoises during the active (nonhibernation) seasons in 2013–2015, and used those data to discriminate movements among activity centers from those within them. We then modeled the probability of movement among activity centers using a suite of covariates describing characteristics of tortoises, natural and anthropogenic landscape features, vegetation, and weather. Multimodel inference indicated greatest support for a model that included individual tortoise characteristics, landscape features, and weather. After controlling for season, date, age, and sex, we found that desert tortoises were more likely to move among activity centers when they were further from minor roads and in the vicinity of barrier fencing; we also found that movement between activity centers was more common during periods of greater rainfall and during periods where cooler temperatures coincided with lower rainfall. Our findings indicate that landscape alterations and climate change both have the potential to impact movements by desert tortoises during the active season. This study provides an important baseline against which we can detect future changes in tortoise movement behavior.