Diets of sympatric Planigale gilesi and P. tenuirostris (Marsupialia: Dasyuridae): relationships of season and body size.

Abstract

The insectivorous diets of Planigale gilesi and P. tenuirostris were studied in the field over a 2-year period by analysis of faeces. Prey items were grouped according to taxonom ic order and size class with the aid of a reference collection. Abundance of potentially available prey was estimated from light trap and pitfall trap data collected during each session of mammal trapping. In all seasons, P. gilesi and P. tenuirostris were generalists with respect to prey type and prey size: prey items in the diet occurred in the same proportions as those in the available prey. Important prey taxa were Coleoptera and Araneida. Large planigales of the same or different species took prey from large size classes that were not utilized by small planigales although all took prey in the small size classes. Approximately 10% of the prey taken by adul ts of the larger species, P. gilesi, was larger than 800 mm3 but P. tenuirostris individuals rarely took prey larger than this size. Body size is a factor that reduces dietary overlap and hence inter- and intraspecific competition.