Microhabitat separation and diel activity patterns of Planigale gilesi and P. tenuirostris (Marsupialia: Dasyuridae).

Abstract

Diel activity patterns and microhabitat use by the partially subterranean dasyurid marsupials Planigale gilesi and P. tenuirostris were studied in captivity. In the laboratory, a chamber was constructed that had a surface area and 'underground' cracks and cavities typical of the species' natural microhabitat. Infra-red light beams monitored the daily activity of individuals over 3 consecutive days under simulated photoperiods and temperatures typical of summer and winter. The larger species, P. gilesi, is more active than P. tenuirostris and, under summer conditions, is nocturnal; in winter it becomes more diurnal. Planigale tenuirostris is primarily nocturnal under summer and winter conditions. Both P. gilesi and P. tenuirostris exhibited short-term activity cycles that respectively, were: in summer 1 h 40 min and 1 h 25 min, and in winter 3 h 21 min and 2 h 56 min. Frequencies of activity bouts showed diel variations in P. gilesi but were constant in P. tenuirostris. Frequencies of rests showed diel variations in both species. Changes in total activity and in the proportion of surface-related activity are closely interrelated between P. gilesi and P. tenuirostris and may operate to reduce possible competitive interactions.