Monday, 18 May 2015

Crickets in the Rain

Late autumn rains bring out the calls of many creatures in the Queensland rainforests. Crickets are contributors to many of the loud sounds we hear after dark. Mole Crickets commence calling on dusk from burrows in the ground. Their calling is low and guttural and continues for 10-15 minutes, then it ceases. They are followed by a number of other cricket species. Among them are the impressive burrowing crickets of the genus Cephalogryllus. At least 13 species occupy the eastern coastal eastern coastal forests of Australia. Each area or mountain range seems to have its own species, and there are some sympatric species. A single species has been described from Western Australia.

Cephalogryllus sp. probably tau Otte & Alexander is commonly heard around Kuranda. Further study is needed to establish its correct identity since a series of different-looking males have been dug from burrows in Kuranda.

This is a large cricket, some 25-27 mm in body length with very sturdy hind legs that are probably used in shaping the burrow. The wings are short and used solely in sound production; the crickets cannot fly. These crickets live in the ground and males sing from the entrance to their burrows on wet nights from February until August. There are many males per unit area in the rainforest but their calls are not synchronised. As a result the background is a continuous din of cricket calls. The ambient "din" can be heard in the recording presented here. The tape recorder was positioned about 16 cm from the entrance to the burrow.
Calling ceases at some stage late in the evening, probably as a result of decreasing ambient temperatures. Females have not been found wandering around after dark as one might expect. The purpose of the calling song supposedly is to attract females for mating. Perhaps, these crickets sing for other reasons, such as territoriality. By morning, the burrows are closed and the occupants remain underground during the day.

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