Monospecific and heterospecific grouping and feeding behavior in grey kangaroos and red-necked wallabies

Benefits of grouping by conspecifics as an anti-predator strategy also shou ld apply in heterospecific associations if species are similar in their vul nerability to predation. I investigated monospecific and heterospecific gro uping by sibling species, eastern (Macropus giganteus) and western grey kan garoos (M.fuliginosus), together with smaller and less social red-necked wa llabies (M. rufogriseus). I observed groups feeding in mornings and evening s on a grassy airfield in the Grampians National Park, western Victoria, Au stralia. Wallabies formed smaller monospecific groups than the kangaroos, m aintained a greater nearest-neighbor distance, and moved more while feeding . Monospecific groups of the two kangaroo species were indistinguishable in size, composition, spacing, and feeding rates. The percentage of individua l grey kangaroos feeding increased with group size in monospecific groups o f up to six. Heterospecific groups of kangaroos formed frequently, and the percentage of individual eastern and western greys feeding was not affected by species composition of groups, suggesting that conspecifics and heteros pecifics were equally valuable as feeding partners. By contrast, the-re wer e few associations between kangaroos and wallabies.