Co-occupancy of spider-engineered burrows within a grassland community changes temporally

Abstract

Burrow-digging organisms act as ecosystem engineers, providing potential habitat to other organisms. In the Mid North region of South Australia, wolf and trapdoor spiders in fragmented grassland communities provide this service. Pygmy bluetongue lizards are an endangered skink, endemic to these grasslands. The lizards obligatorily use burrows dug by these spider groups as refuges, basking sites and ambush points. We investigated the occupancy of these spider burrows by lizards and other organisms within the grassland community, identifying the occasions that burrows were shared by multiple taxa. We found that the lizards and trapdoor spiders are predominantly solitary, while wolf spiders co-shared burrows more frequently with either weevils or snails. There were numerous taxa that were found to regularly co-share with other taxa, particularly snails, centipedes and weevils. There was a strong temporal influence on burrow sharing, with most co-sharing occurring late in summer. This study provides an insight into the use of burrows by the lizards and co-existing taxa within these grassland communities. The dynamics of burrow-use by other taxa have the potential to influence long-term conservation of these lizards as burrow availability is crucial to their survival in these grasslands.