Abstract
Alpine regions harbour some of Earth’s most significant ecosystems. Unfortunately, these precious biological communities are globally vulnerable to anthropogenic threats such as habitat modification and climate change. Many of their specialised occupants are threatened with extinction, including reptiles. Alas, the cryptic behaviour of reptiles, combined with the inaccessibility of alpine ecosystems, makes herpetological research very difficult. Aotearoa/New Zealand epitomises these circumstances. At least 15 gecko species (Reptilia: Diplodactylidae) occupy alpine ecosystems in New Zealand and several of these species are thought to be threatened with extinction, including one of New Zealand’s most enigmatic alpine gecko species, the hura te ao gecko (Mokopirirakau galaxias). Hura te ao geckos were discovered in 2018 and their habitat use, and behaviour, is yet to be fully elucidated. Virtually nothing is known about their ecological relationships with sympatric gecko species, such as the Southern Alps gecko (Woodworthia “Southern Alps”).
In this thesis, I investigated the ecology of hura te ao geckos and Southern Alps geckos. To improve our understanding of their emergence behaviour and habitat use, I conducted night-time gecko surveys during the 2022 austral summer at several alpine localities in North Otago and South Canterbury. When I sighted geckos, I collected data for a range of weather variables and characterised gecko habitat use within circular sampling quadrats. I also tracked a subset of both gecko species using fluorescent pigments. The number of hours elapsed after sunset was the most important factor influencing hura te ao gecko sightings and generalised additive models (GAMs) indicated that gecko activity was not heavily affected by air temperature (within the observed range of temperatures). The probability of detecting a hura te ao gecko, relative to a Southern Alps gecko, appeared to be closely associated with the number of hours after sunset, humidity, and the site at which geckos were found. Hura te ao geckos were more likely to be detected than Southern Alps geckos at high and low humidities, but had similar detection probabilities at moderate humidities. Behavioural differences between the two gecko species imply some level of niche partitioning. Rock tors and talus were the most important components of hura te ao gecko habitat use and although fewer geckos were detected in talus habitats compared to tor habitats, fluorescent-pigment tracking indicated that talus was used extensively by most hura te ao geckos. Therefore, observer bias may be influencing our ability to detect these cryptic, alpine geckos. This thesis presents the most comprehensive information about hura te ao gecko ecology to date and ultimately contributes to our growing understanding of alpine gecko ecology.