Male-biased movement in pygmy bluetongue lizards: implications for conservation

Abstract

Context Translocation has become an increasingly common tool in the conservation of species. Understanding the movement patterns of some species can be important to minimise loss of individuals from the translocation release site. Aims To describe seasonal and sex-biased movements within populations of an endangered Australian lizard. Methods We monitored seasonal movement in the endangered pygmy bluetongue lizard (Tiliqua adelaidensis) by using pitfall trapping, with a total of 49 440 trap-nights from three sites over 2 years. Other studies have shown that individual pygmy bluetongue lizards normally remained closely associated with their spider burrow refuges, with very little movement. Thus, we interpreted any captures detected through pitfall trapping as out of burrow movements. We investigated whether there was any seasonal, age or sex bias in moving individuals. Key results We found that male pygmy bluetongue lizards were more likely to move than were females. After adults, neonates were the second-most captured age class. Spring was the peak movement time for adults, whereas movement of neonates occurred in autumn. Key conclusions The majority of movement can be attributed to males in the breeding season, whereas females move very little. Implications The present study provides some baseline data that would allow more informed decisions about the most appropriate individuals in a population to choose for a translocation program and the times to conduct translocations to allow the maximum chance for establishment.

Impact of foxes digging for the pygmy bluetongue lizard (Tiliqua adelaidensis)

“…Lizards occasionally leave their burrows temporarily to defecate or stalk close-by prey, but burrows only seem to be permanently vacated if they get filled in, get too small (for growing juveniles and subadults) or during the spring mating season when predominantly males move around to locate females (Ebrahimi, Godfrey, Fenner, & Bull, 2014;Fenner & Bull, 2011a;Milne et al, 2003;Schofield, Fenner, Pelgrim, & Bull, 2012).…”

Dynamics of a Temperate Grassland Reptile Community in the Mid-North of South Australia

“…These sites have been previously described by Fenner and Bull (2007) and Schofield et al (2012). Both are located in a remnant of native grassland habitat in the mid north of South Australia, within 13 km of Burra (33°42´S; 138°56´e), and they were separated from each other by ploughed cereal cropping fields.…”

“…After processing, reptiles were released on the opposite side of the fence line to reflect the direction they had been travelling when trapped. in the analysis, data were grouped into trapping periods, according to the time of trapping, early (Sep -nov), middle (dec-Jan) and late (Feb -march) in the season, and we estimated trapping rate as the number of captures per 1000 trap days (Schofield et al, 2012). due to the low number of captures in September (n=16) we pooled September and october captures in the analyses.…”

Interactions between pygmy bluetongue lizards and co-existing species

“…In that case we may have underestimated the frequency of spider and lizard interactions generated by more mobile subadults and juveniles in the lizard population (Schofield et al 2012). …”

“…. Lizards occasionally move out of their burrows to defecate, lunge at passing invertebrate prey, or to seek mating partners for a brief period in the spring, but otherwise are almost entirely confined to their burrows, the burrow entrances and an extremely small area around the burrow entrance (Milne et al, 2003b;Fenner et al, 2007;Fenner and Bull, 2011;Schofield et al, 2012;Ebrahimi et al, 2014). As a consequence, we assume that most of their interspecific interactions also take place around the burrow entrance.…”