Body Size-Prey Relationships in Insectivorous Marsupials: Tests of Three Hypotheses

摘要: There is a strong positive correlation between the body sizes of dasyurid marsupials and mean their invertebrate prey. This study tests three hypotheses proposed to explain this relationship, using 21 species dasyurids (body mass range: 5- 200 g) throughout continental Australia: (1) maximum prey size that can be physically handled increases with due restricted gapes or forces biting smaller dasyurids; (2) maximizes rate energy intake varies size, animals preferentially consuming most profitable prey; (3) en- countered during foraging vary size. largest offered in laboratory, which were similar potentially available field. The second third supported. Indi- viduals maximized rates gain captivity by feeding on small prey, trails field traversed microhabitats where potential encountered was (2-4 mm long). In contrast, larger preferred large obtained greater from them, foraged lengths averaged -6 mm. tendency for include progressively diets than available, average, along trails. may reflect increasing selectivity However, it also reduced susceptibility predation increased competitive ability productive microhabitats, hence size-based advantage encountering These results indicate net yield use different are important determinants size-prey relationship marsupials.