Microhabitat selection by wolf spiders and dunnarts 

The lesser hairy­footed dunnart (Sminthopsis youngsoni, Dasyuridae) is a generalist marsupial insectivore in arid Australia, but consumes wolf spiders (Lycosa spp., Lycosidae) disproportionately often relative to their availability. This project tested the hypothesis that this disproportionate predation is a product of frequent encounter rates between the interactants due to high overlap in their diets and use of space and time. This data set focuses on overlap in the use of different microhabitats of wolf spiders (Lycosa spp.) and the lesser hairy­footed dunnart (Sminthopsis youngsoni) in the Simpson Desert, south­western Queensland Australia. Microhabitat use was determined by estimating the percentage cover of seven microhabitat variables and distance to nearest cover along trails left by individuals of each species­ group and a randomly orientated (control) trail for each actual trail as a measure of the availability of each microhabitat within the local environment. Trail length was also recorded and data was collected across 16 trapping grids at Main Camp during July and October (winter and Spring) in 2017. Differences in microhabitat use between trail types (actual vs control) and species (lycosids vs dunnarts) were assessed using non­metric multidimensional scaling (NMDS) and permutational analyses of variance (PERMANOVA). These analyses were performed using this data. 

We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. 

This is part of a project titled, "Exploring the interaction between the lesser hairy­footed dunnart and lycosids in the Simpson Desert". The lesser hairy­footed dunnart (Sminthopsis youngsoni) is a common generalist insectivore in arid Australia that consumes wolf spiders (Lycosa spp.) disproportionately often relative to their availability. This study aimed to uncover the underlying mechanisms that drive this observed pattern of selective predation. 

Visual estimation of percentage cover of microhabitat attributes: [1] Animal Trapping Individual S.youngsoni were live­captured in pitfall traps on 16 trapping grids located 0.62 km apart at Main Camp during July and October 2016. Each grid comprised 36 pitfall traps in a 6 × 6 formation with traps set 20 m apart. Grids encompassed all dune zones (crest, side and swale) and covered 1 ha. A trap consisted of a PVC pipe 60 cm deep × 16 cm diameter, dug flush with the sand surface and overlain by a 5 m long, 300 mm high drift fence of aluminium flywire to increase trapping efficiency. Captured individuals were identified, weighed, sexed and reproductive status checked, and then given a unique ear clip. Lycosid spiders were collected opportunistically from vertebrate pitfall traps (see above) or through active searches over multiple nights around Main Camp. [2] Tracking of Individuals To quantify the degree of microhabitat selectivity displayed by S. youngsoni, movement patterns of captured individuals were quantified using spools and lines (n = 26, 15 in July and 11 in October 2016). Prior to release, a 2­ply cotton bobbin spool (Coats Australia Pty, Sydney, Australia) was secured using non­toxic cyanoacrylate glue (Selley's Quick Fix superglue) and positioned so as not to impede head or leg movement. Spools were adjusted to weigh ~6% of individual body mass (mean ± SE; 0.65 ± 0.18 g) and secured with tape. Individuals were released with spools within 3 h of dusk. Prior to release, a 3 × 3 mm square of silver reflective tape was attached to the opisthosoma of each lycosid using non­toxic cyanoacrylate glue to increase the detectability of spiders when tracking them in low light conditions. Spiders were released near their capture site between 20:00 h and 23:00 h around Main Camp, and followed and observed under red torchlight at a distance of 2­3 m to minimise disturbance. A flag was deployed at the start of each spider's trail and then at ~2.5 m intervals to record the path taken, with a total of 12 flags deployed per trail. Spiders were observed for ~1 h or until all 12 flags were deployed. [3] Microhabitat Assessments The following day, spool lines and spider trails were followed and the cumulative distance travelled by each released animal measured to the nearest 0.1 m using a tape measure. Additionally, percentage cover of seven different microhabitat types was estimated visually using a 0.5 × 0.5 m quadrat at fixed 2.5 m intervals along the spool trails. These microhabitats were: live spinifex, dead spinifex, ground cover, shrub cover, dead wood, all other vegetation, and bare ground. In order to assess the degree of microhabitat selectivity exhibited by both species, a single control trail for each actual trail left by an individual was also scored as a measure of the availability of each microhabitat within the local environment. Control trails were set to be the same length as actual trails and microhabitat scoring was consistent with that employed for tracked trails, thus presenting a standardised method for comparison between the two trail types.