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Kangaroos – The 100 Days Project: Day 24 [77]
The Major Roos:
The Eastern Grey Kangaroo
Photo: Ray Drew
Kangaroos are not only the largest of the macropods, but the largest of the marsupials generally. Although there are clines (gradations in one or more characteristics within a species, especially between different populations) across their ranges, there are in fact only four main species in Australia: the Eastern Grey Kangaroo, the closely-related Western Grey Kangaroo, the Red Kangaroo and the Wallaroo/Euro (or Hill Kangaroo).
The Grey Kangaroos split from the rest of the macropus eight to nine million years ago (Meredith et al. 2008); the Red Kangaroo and Wallaroos appeared in the Pleistocene about five million years ago. We’ll begin with the Eastern Grey for purely selfish reasons, as it is the most populous in my own part of Australia, and are the one in my own gully.
Although the Latin name for the species, Macropus giganteus giganteus, might seem to suggest otherwise, the Eastern Grey Kangaroo – sometimes called ‘the Great Grey Kangaroo’ or the ‘Scrub Kangaroo’ (and ‘the Forester’
in Tasmania) – is commonly thought to be second in size to the Red Kangaroo (we are talking about males here: taxonomy can be so sexist). My impression, however, is that it’s pretty much touch-and-go, especially given the way the male-only ‘harvesting’ policies are messing with size and gene pool. A typical large male Eastern Grey will reach 66 kilograms in weight and (on tip-toe) two metres in height (a problem, how one measures a kangaroo’s height/length), though weights of up to 90 kilograms have been recorded (and we are about to meet Ned, who supposedly weighed in – and I have no reason to doubt it – at 95 kilograms).
The favoured habitat of the Eastern Grey is the inland plains and open woodlands of the interior and the grassy forests and glades of coastal eastern Australia, where the annual rainfall is c.250 millimetres and above, in which areas it can tolerate all altitudes up to the subalpine. Their historic distribution covered approximately one-third of the continent, from the east coast through to a line running roughly from Cooktown on Cape York south to eastern South Australia however habitat loss and persecution have rendered their distribution today into a patchy and fragmented state.
Eastern Grey Kangaroos – another figure taking a bashing from ‘harvesting’, male-only or otherwise – can supposedly live to 15-20 years in the wild. Their individual range, when not disturbed by one mode or another of human predation, is approximately two to ten square kilometres, though young males may explore much farther, and if undisturbed females can happily occupy a home range on only one square kilometre. Their mob/pod size is often given as around ten individuals, with a predominance of women and children under the aegis of a ‘boss’/‘alpha’ male. Historic records and occasionally in the modern age gatherings can be much larger.
Photo: Stella Reid, Wildhaven
But now for the question of questions: how to tell an Eastern Grey from other species of kangaroo? Well, for a start, they (and their closest relative the Forester kangaroo) are grey, though that isn’t going to get us very far: the female Red Kangaroo is also a bluish-grey, and the Western Grey Kangaroo (Macropus fulginosis) can be a bit, well, browny-red, but is also largely grey. It may be of more use to know that the Eastern Grey has dark tips to his/her paws, feet and tail, that the nails (and what nails they are!) on the fore- and hind-limbs are larger than those of Red Kangaroos or Wallaroos/Euros, and that Eastern Grey males tend to have much longer forearms than Red Kangaroo or Wallaroo/Euro males.
But, like most such distinctions of shade and proportion, even these features may not be much use to us unless we have members of the other species nearby for comparison, so here’s a trick: the Eastern Grey Kangaroo and its (very) close relatives the Forester and the Western Grey Kangaroo have hairy noses. You can tell them very easily from a Wallaroo/Euro, because a Wallaroo/Euro has a bald, i.e. hairless, nose-tip. The technical term for the nose-tip is rhinarium. Wallaroo/Euros have a
hairless rhinarium, Red Kangaroos have hair only on the top-half of their rhinarium, and the Great Grey Kangaroos have hair over all the rhinarium except for a thin strip along the upper-edge of each nostril. Here’s Ned again to demonstrate almost definitively:
Photo: Stella Reid, Wildhaven
That’s not an end to the differences and distinctions: the Great Greys hop slightly differently to Reds on the one hand and Wallaroos on the other; their offspring develop more slowly, and, perhaps most significantly, given the claims made for them by those who would exploit them, the Eastern Grey females, unlike those of the Red kangaroo and the Wallaroos/Euros, exhibit embryonic diapause only rarely (and their cousins the Western Greys not at all).
Doubtless if we could talk with the kangaroos themselves they would tell us of differences we haven’t even dreamt about. Perhaps even some gossip about their closer relatives. The Eastern Greys are part of a family within Australian kangaroos that also includes the Western Grey, as already indicated, and the Forester kangaroo (Macropus giganteus tasmaniensis), each of whom, out of respect, I will leave for a separate post.
By way of a non-conclusion I’ll leave you with two other Eastern Grey details: that Skippy was an Eastern Grey, and that it was an Eastern Grey female who registered the highest kangaroo-speed that we human-animals have so far managed to record: 64 kph.
Ref.: Robert W. Meredith et al. 'A phylogeny and timescale for the living genera of kangaroos and kin (Macropodiformes : Marsupialia) based on nuclear DNA sequences.' Australan Journal of Zoology 56 (2008): 395-410