Survival and growth of tuataraSphenodon punctatusfollowing translocation from the Cook Strait to warmer locations in their historic range

Abstract

Post-translocation monitoring is fundamental for assessing translocation success and identifying potential threats. We measured outcomes for four cohorts of tuatara Sphenodon punctatus translocated to warmer climates outside of their ecological region, to understand effects of climate warming. Translocation sites were on average 2–4 °C warmer than the source site. We used three short-term measures of success: survival, growth and reproduction. Data on recaptures, morphometric measurements, and reproduction were gathered over 2.5 years following release. Although decades of monitoring will be required to determine long-term translocation success in this species, we provide an interim measure of population progress and translocation site suitability. We found favourable recapture numbers, growth of founders and evidence of reproduction at most sites, with greater increases in body mass observed at warmer, less densely populated sites. Variable growth in the adult population at one translocation site suggested that higher population density, intraspecific competition, and lower water availability could be responsible for substantial weight loss in multiple individuals, and we make management recommendations to reduce population density. Overall, we found that sites with warmer climates and lower population densities were potentially beneficial to translocated tuatara, probably because of enhanced temperature-dependent and density-dependent growth rates. We conclude that tuatara could benefit from translocations to warmer sites in the short term, but further monitoring of this long-lived species is required to determine longer-term population viability following translocation. Future vulnerability to rising air temperatures, associated water availability, and community and ecosystem changes beyond the scope of this study must be considered.

Initial collection, characterization, and storage of tuatara (Sphenodon punctatus) sperm offers insight into their unique reproductive system

“…Extreme distributional and demographic declines of tuatara populations prompted a massive conservation effort by the early-1990s [12]. While numerous conservation techniques have proven effective at restoring tuatara populations, such as mammal eradications, translocations, and headstarting programs [13][14][15][16][17], there is still much work to be done, including around ARTs.…”

Novel Conditions in Conservation Translocations: A Conservative-Extrapolative Strategic Framework

“…Several mainland locations have also had occasional incursions of larger introduced mammals such as Norway rats (Rattus norvegicus), ship rats (R. rattus), and stoats (Mustela erminea), but control of these predators has been needed to minimise the threat to tuatara. Preliminary survivorship of tuatara at monitored mainland locations is encouraging (McKenzie, 2007;Cree, 2014;Jarvie et al, 2015Jarvie et al, , 2016Jarvie et al, , 2021Price et al, 2020), although continued vigilance and monitoring for introduced mammals remains necessary.…”

Reproductive Fitness in Male Tuatara (Sphenodon punctatus) and its Implications

“…Extreme distributional and demographic declines of tuatara populations prompted a massive conservation effort by the early-1990s (Miller et al, 2012). While numerous conservation techniques have proven effective at restoring tuatara populations, such as mammal eradications, translocations, and headstarting programs (Cree et al, 1995;Gaze, 2001;Jarvie et al, 2015;Nelson et al, 2002;Price et al, 2020), there is still much work to be done, including around ARTs.…”