Predictors of translocation success of captive‐reared lizards: implications for their captive management

Comparing reintroduction strategies for the endangered San Francisco gartersnake (Thamnophis sirtalis tetrataenia) using demographic models

For endangered species persisting in a few populations, reintroductions to unoccupied habitat are a popular conservation action to increase viability in the long term. Identifying the reintroduction strategy that is most likely to result in viable founder and donor populations is essential to optimally use resources available for conservation. The San Francisco gartersnake (Thamnophis sirtalis tetrataenia) is an endangered sub-species that persists in a small number of populations in a highly urbanized region of California. Most of the extant populations of San Francisco gartersnakes have low adult abundance and effective population size, heightening the need for establishment of more populations for insurance against the risk of extinction. We used simulations from demographic models to project the probability of quasi-extinction for reintroduced populations of San Francisco gartersnakes based on the release of neonate, juvenile, adult, or mixed-age propagules. Our simulation results indicated that the release of head-started juveniles resulted in the greatest viability of reintroduced populations, and that releases would need to continue for at least 15 years to ensure a low probability of quasi-extinction. Releasing captive-bred juvenile snakes would also have less effect on the viability of the donor population, compared to strategies that require more adult snakes to be removed from the donor population for translocation. Our models focus on snake demography, but the genetic makeup of donor, captive, and reintroduced populations will also be a major concern for any proposed reintroduction plan. This study demonstrates how modeling can be used to inform reintroduction strategies for highly imperiled species.

Nomenclature of supra-generic units within the Family Scincidae (Squamata)

The modern classification of skinks is based on a nomenclature that dates to the 1970s. However, there are a number of earlier names in the family group that have been overlooked by recent workers. These names are identified and their validity with respect to the International Code of Zoological Nomenclature investigated, along with their type genera. In most cases, use of these names to supplant junior synonyms in modern day use is avoidable by use of the Reversal of Precedence articles of the Code, but the names remain available in case of future divisions at the tribe and subtribe level. Other names are unavailable due to homonymy, either of their type genera or the stems from similar but non-homonymous type genera. However, the name Egerniini is replaced by Tiliquini, due to a limited timespan of use of Egerniini. A new classification of the Family Scincidae is proposed, providing a more extensive use of Code-regulated levels of classification, including tribes and subtribes, and a detailed synonymy provided for each taxonomic unit.

Heat and water loss versus shelter: a dilemma in thermoregulatory decision making for a retreat-dwelling nocturnal gecko

Understanding the interaction between upper voluntary thermal limit (VTmax) and water loss may aid in predicting responses of ectotherms to increasing temperatures within microhabitats. However, the temperature at which climate heating will force cool-climate nocturnal lizards to abandon daytime retreats remains poorly understood. Here, we developed a new laboratory protocol for determining VTmax in the retreat-dwelling, viviparous Woodworthia 'Otago/Southland' gecko, based on escape behaviour (abandonment of heated retreat). We compared the body temperature (Tb) at VTmax, and duration of heating, between two source groups with different thermal histories, and among three reproductive groups. We also examined continuous changes in Tb (via an attached biologger) and total evaporative water loss (EWL) during heating. In the field, we measured Tb and microhabitat thermal profiles to establish whether geckos reach VTmax in nature. We found that VTmax and duration of heating varied between source groups (and thus potentially with prior thermal experience), but not among reproductive groups. Moreover, geckos reached a peak temperature slightly higher than VTmax before abandoning the retreat. Total EWL increased with increasing VTmax and with the duration of heating. In the field, pregnant geckos with attached biologgers reached VTmax temperature, and temperatures of some separately monitored microhabitats exceeded VTmax in hot weather implying that some retreats must be abandoned to avoid overheating. Our results suggest that cool-climate nocturnal lizards that inhabit daytime retreats may abandon retreats more frequently if climate warming persists, implying a trade-off between retention of originally occupied shelter and ongoing water loss due to overheating.