Mouse spider burrows
Why 'mouse' spiders? No good reason. But possibly the name was given for the large, supposedly 'mouse-like' burrows built by the big inland Red-headed Mouse Spiders. These large, silk-lined burrows vary from 20 to 55 cm deep and are widest in the entrance and bottom chamber areas. A side chamber extends off the main burrow shaft, usually closed by a trapdoor. It provides a refuge from predators and a safe place for the egg sac and spiderlings.
However, the burrow's most unusual feature are the two surface trapdoors set almost at right angles to each other. The silk and soil trapdoors often merge well with the ground, making them hard to see (and increasing the impression of scattered rather than aggregated burrow sites, making accurate estimates of their abundance difficult). They may be thin and wafer-like or thick and plug-like. Having two doors probably increases both prey catching area and efficiency. A few silk triplines may extend outwards from the entrances. These can help alert the spider to approaching prey or male spiders and also help with surface navigation while hunting. Prey is usually ambushed from within the safety of the trapdoor 'hides', but mouse spiders have been observed foraging outside the burrow at night. With their powerful jaws and venom, they can tackle prey ranging from ants, beetles and spiders to small lizards and frogs.
Little is known about the burrows of other species. The forest dwelling Eastern Mouse Spider appears to have a single, flap-like door and a shallow burrow with a side chamber. Unlike other species, this mouse spider has occasionally been reported living in large aggregations. Recently, almost 300 specimens were collected from the backyard of a house on the central coast of New South Wales after flooding rains drove the animals from their burrows.
