Burrowing in captive juvenile Desertas wolf spiders Hogna ingens

Abstract

The Desertas wolf spider Hogna ingens, endemic to Desertas Grande in Madeira, relies on burrows under rocks and crevices for protection. Studies at Bristol and Whipsnade Zoos investigated substrate preferences and various physical aspects of the environment that might promote burrowing behaviour. It is important that habitat preferences are understood for both captive husbandry and for future reintroductions. Two choice-experiments were conducted to separately investigate (i) preferences for types of soil substrate and (ii) the effect of the presence of burrow anchor points, which provide structural support for the burrow, on burrow location. In addition, the effects of the (i) type of substrate and (ii) depth of substrate on burrow occurrence were separately investigated. In each study the onset of burrowing and characteristics of the burrow were recorded. Results show that both the type and depth of substrate impacts the construction of burrows. Optimum substrate depth was over 50 mm and lighter, loosely packed substrates were favoured in both studies. The results of a binomial generalised linear model showed that the size of stones and the clutch the spider was born of significantly explained 76% (pseduo-R2=0.76) of the variation in likelihood that a spider would use stones as structural supports (X2; df=1, P>0.001). Husbandry guidelines for this species will be reviewed in the light of these results and evidence will be used to inform future in-situ conservation efforts.