Weight watching in burrows: variation in body condition in pygmy bluetongue lizards

Abstract

8The pygmy bluetongue lizard, Tiliqua adelaidensis, is an endangered scincid lizard which occurs in 9 remnants of natural grasslands in the mid-north of South Australia. We assessed the factors affecting body 10 condition of male and female lizards, using body size residuals as an index, over five sampling years. We 11 included sex, phenotypic (patterned or plain morphs), temporal (sampling year and activity period within 12 year), and climatic factors in our analyses. The results indicated that sampling year and activity period 13 within the year were the two most important factors influencing variation in body condition of both male 14 and female lizards over the period of the study. There were similar trends when we considered females 15 separately in each of three stages of their reproductive cycle (pre-partum, gravid, post-partum). None of 16 the analyses showed any significant effect of phenotype on body condition. Winter-spring rainfall was 17 positively correlated with body condition of females in the pre-partum period, but showed no significant 18 effect on mean body condition of any other grouping of adult lizards, nor a consistent direction of 19 correlation among the different subsets of adult lizards that we considered. The substantial annual 20 variations in the body condition of lizards, although of uncertain cause, provide important information for 21 conservation managers who monitor persisting populations of this endangered species. 22 2

Effects of grazing regime on the relative body mass of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)

“…These results are consistent with patterns previously reported by Shamiminoori et al . (), who suggested higher prey abundance and more feeding opportunities during spring, as an explanation for higher body condition in the early part of the spring–summer activity season. Our results show that grasshoppers, which are a major part of the lizard diet, are less abundant but significantly larger in spring than later in the activity season, indicating that it is the quality and size, and not the abundance of prey, that enable the lizards to build up energy stores.…”

“…Previous studies of this species have used a body condition index based on the residuals of the regression of mass and SVL (Fenner & Bull ; Shamiminoori et al . ) but this regression‐based index is not suitable for data from the same individuals repeated over time (Green ). Analyses used the mean values of the relative body mass per paddock in each survey, rather than the individual values per lizard.…”

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

“…The pygmy bluetongue lizard (Tiliqua adelaidensis), with a mean adult snout-vent length of 95 mm, is the smallest member of the genus Tiliqua (Shamiminoori, Fenner, & Bull, 2014). With most of its former habitat now converted into crop lands, this scincid lizard is currently considered endangered both in South Australia and internationally (International Union for Conservation of Nature, 2015) and is restricted to a few remaining patches of native grassland in the mid-north region of South Australia.…”

Population augmentation had no effect on the abundance or body condition of conspecifics and co‐occurring lizard species in a native grassland community

“…Whilst we cannot directly discuss the impact upon the fitness of the co‐existing species, we use this approach to examine fitness metics, such as body condition, as indirect indicators of body health as a proxy for fitness (Bonnet & Naulleau, ; Nagy et al ., both cited by Shamiminoori et al . ).…”