Burrows of desert-adapted frogs, Neobatrachus aquilonius and Notaden nichollsi

The non-cocooning frogs, Notaden nichollsi and Uperoleia micromeles, and the cocoon-forming frog, Neobatrachus aquilonius , burrow underground to survive in the hot, dehydrating arid interior of Australia. By four to six months after these frogs had burrowed, the only surface evidence that a frog had dug a vertical burrow was either a small raised-side crater ranging from 50 – 60 mm in diameter or a shallow depression the same size with a less compacted centre. Notaden nichollsi and U. micromeles were dug from poorly-defined, sand-filled burrows in sandy soil (1.4 – 4.1% clay and silt, 95.9 – 98.4% sand) at 600 to 2400 mm below the surface. Multiple N. nichollsi and U. micromeles were located in single burrows. In contrast, N. aquilonius were found in clay soil (12.5 – 17.9% clay and silt, 82.1 – 87.5% sand) in burrows 280 to 1200 mm deep. At a clay pan site only a single N. aquilonius was found in each well-defined, loosely filled burrow that we excavated. From a swale site, on one occasion we found two N. aquilonius in one burrow, and on another occasion we found a N. aquilonius and a N. nichollsi in the same burrow