Bipedal versatility in ruminants, part 3

Why is there such a great difference in bipedal versatility between deer and bovids?

In general, deer tend to live as one species (or two if sufficiently different in body size) per type of environment. They have broad niches in this context. By contrast, bovids tend to live in species-rich communities, in which the species share a given environment by partitioning the resources. One of the ways that food is partitioned in bovid communities is by height above ground.

Let us take Kruger Park in South Africa as an example. The ruminants most comparable with deer in this savanna are, from smallest to largest, the steenbok (Raphicerus campestris, and and and, the impala (Aepyceros melampus,, the greater kudu (Strepsiceros strepsiceros, and and and and, and the southern giraffe (Giraffa giraffa).

Each has a typical height-zone for foraging, particularly in the dry season when food is scarcest (, and none tries to extend its foraging height by standing bipedally, even with the fore legs propped on branches. There are categorically no photos of such postures.

In other words, bovids tend to be specialised in terms of the range of heights at which they forage, whereas deer tend to exploit the widest height-range allowed by their bipedal versatility. This applies even to the gerenuk, because this species not only forages bipedally, but is far more specialised for doing so than is any deer.

Given this versatility, it is understandable that deer also use free-standing bipedally in their social behaviour, in a way never seen in e.g. steenbok, impala, greater kudu or other bovids - including the gerenuk.

Wild goats are more rock-adapted than any deer; the scaling of steep rocky slopes may require postural flexibility which has been retained and perhaps enhanced through domestication. However, what wild goats share with deer is that they tend to be the only ruminants in the environments they inhabit, which means that they tend to forage over a wide height-range by means of some degree of bipedal versatility.

Posted on September 04, 2021 03:57 PM by milewski milewski


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