The lesser hairy-footed 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 the dietary aspect. Specifically, invertebrate pitfall trapping was employed to quantify food availability and selectivity for both wolf spiders and S.youngsoni. Pitfall traps were deployed along trails left by tracked individuals, as well as control trails, of both species groups in the north-western Simpson Desert, Queensland. In total, invertebrate pitfall traps were deployed along 11 S.youngsoni and 8 lycosa trails in October 2016. Invertebrates were identified to the level of "Order", except for spiders (Order: Arachnida) and bees, wasps and ants (Order: Hymenoptera) which were identified to the "Family" level using identification keys and were also counted and grouped into seven size classes. This data was used for the following analyses: [1] a two-way analysis of variance (ANOVA) to test whether total numbers of arthropods differed between trail type and species, [2] non-metric multidimensional scaling (NMDS) and [3] permutational analysis of variance (PERMANOVA) to test whether assemblages of arthropod prey and prey sizes differed between the two trail types for each species and between each species.
Credit
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.
Purpose
This is part of a research project titled, "Exploring the interaction between the lesser hairy-footed dunnart and lycosids in the Simpson Desert". The lesser hairy-footed 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.
Lineage
Invertebrate pitfall trapping: [1] Animal Trapping Individual S. youngsoni were live-captured 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 2-ply cotton bobbin spool (Coats Australia Pty, Sydney, Australia) was secured using non-toxic 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 1-3 h of dusk. Prior to release, a 3 × 3 mm square of silver reflective tape was attached to the opisthosoma of each lycosid using non-toxic 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 2-3 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] Invertebrate Pitfall Trapping Pitfall traps were deployed every 5 m along dunnart movement trails and randomly-oriented control paths, and at every third flag along actual and control paths of spiders. A trap comprised a plastic vial (40 mm diameter × 100 mm deep) filled with ~80 mL of 3% formalin solution. Pitfall traps were buried flush with the soil surface to maximise capture efficiency and left in situ for three nights. A minimum of three vials was deployed along the trails taken by each dunnart and spider, as well as along their corresponding control trails. Lids were placed over open traps each morning and removed late each afternoon to ensure that only nocturnal invertebrates were collected. Thus, sampling was intended to reflect the actual prey types potentially available to dunnarts and spiders. After collection from the field, invertebrate pitfall vials were rinsed in water and 80% ethanol before inspection. Invertebrates were identified to Order, except for spiders (Order: Arachnida) and bees, wasps and ants (Order: Hymenoptera) which were identified to Family using identification keys and were counted and grouped into seven size classes based on total body length from head to abdomen, with the exclusion of appendages (antennae, legs) to determine if the predators partition prey based on size.
Authors
Point of Contact
Publisher
Collections