A Face in the Crowd: A Non-Invasive and Cost Effective Photo-Identification Methodology to Understand the Fine Scale Movement of Eastern Water Dragons

Abstract

Ectothermic vertebrates face many challenges of thermoregulation. Many species rely on behavioral thermoregulation and move within their landscape to maintain homeostasis. Understanding the fine-scale nature of this regulation through tracking techniques can provide a better understanding of the relationships between such species and their dynamic environments. The use of animal tracking and telemetry technology has allowed the extensive collection of such data which has enabled us to better understand the ways animals move within their landscape. However, such technologies do not come without certain costs: they are generally invasive, relatively expensive, can be too heavy for small sized animals and unreliable in certain habitats. This study provides a cost-effective and non-invasive method through photo-identification, to determine fine scale movements of individuals. With our methodology, we have been able to find that male eastern water dragons (Intellagama leuseurii) have home ranges one and a half times larger than those of females. Furthermore, we found intraspecific differences in the size of home ranges depending on the time of the day. Lastly, we found that location mostly influenced females’ home ranges, but not males and discuss why this may be so. Overall, we provide valuable information regarding the ecology of the eastern water dragon, but most importantly demonstrate that non-invasive photo-identification can be successfully applied to the study of reptiles.

Photographic identification of individuals of a free‐ranging, small terrestrial vertebrate

“…In comparison, the eastern water dragon's coarse surface structure was not reported to cause reflective issues in photos or be problematic for the I 3 S software (Gardiner et al. 2014). In our study, an insufficient number of high quality reference images likely contributed to the low score in the self evaluation results.…”

“…One study showed photo‐identification could be used to track movements of free‐ranging eastern water dragon Intellagama leseureuii and calculate their home ranges (Gardiner et al. 2014). However, few reports have investigated the broader limitations of the technique or evaluated alternative ways of using the technique for a free‐ranging reptile.…”

Polyandry in dragon lizards: inbred paternal genotypes sire fewer offspring

“…For example, at Roma Street Parkland, there is a population in excess of 580 animals and females may overlap with up to 42 males (Gardiner et al. 2014). However, multiple matings as a consequence of frequent encounters may not be the only model that best explains water dragon mating dynamics because males control space and, as a result, females may be able to avoid particular males by closely associating with the dominant male.…”

Sex-Specific Patterns in Abundance, Temporary Emigration and Survival of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in Coastal and Estuarine Waters

“…Photo-ID has been widely used across taxonomic groups, such as terrestrial and marine mammals (Kelly, 2001;Langtimm et al, 2004), reptiles (Schofield et al, 2008;Gardiner et al, 2014) and fish (Couturier et al, 2014;Kanive et al, 2015). Photo-ID is considered a largely non-invasive method by which animals are initially "captured" in photographs, and subsequently matched through photographic "recaptures" to create an individual's capture history.…”