Walking gaits in Cervidae: deer tend to cross-walk, as opposed to the ambling typical of many bovids, part 3: Discussion

...continued from https://www.inaturalist.org/journal/milewski/91630-walking-gaits-in-cervidae-deer-tend-to-cross-walk-as-opposed-to-the-ambling-typical-of-many-bovids-part-2-odocoileinae#

DISCUSSION

https://www.inaturalist.org/observations/60154859

It is unsurprising that I have found photographic evidence of all species of deer semi cross-walking.

In ungulates generally, the least remarkable gait is a semi cross-walk.

This is because

  • the semi cross-walk is an intermediate, unspecialised gait, neither as committed to stability as the cross-walk, nor as committed to energetic efficiency as the amble, and
  • in unguligrade mammals, the functional equivalent - simply owing to proportional leg-length - of the normal 'one step at a time' walking gait of digitigrade mammals (e.g. Felidae ), is a semi cross-walk.

However, there is a divergence among ruminants in walking gaits, with cover-dependent species erring towards cross-walking, and 'plains game' erring towards ambling.

In bovids, this divergence/dichotomy results in whole tribes, e.g. Alcelaphini and Hippotragini (https://www.inaturalist.org/journal/milewski/85349-gaits-and-other-aspects-of-locomotion-in-hippotragin-bovids#), that consistently amble.

For example:

This is behaviourally and ecologically correlated, as follows:

  • Cover-dependent bovids tend to be nocturnal, solitary, and camouflage-coloured, with eyes facing somewhat forward.
  • By contrast, 'plains game' are adapted to living in the open, with diurnal habits, gregariousness, conspicuous colouration, and eyes so far on the sides of the head that they can scan behind and in front at the same time.

The pronghorn (Antilocapra americana) belongs to a different family, viz. Antilocapridae. It conforms to the 'plains game' category, and ambles accordingly (https://es.123rf.com/photo_30436381_pronghorn-antelope-p%C3%A9rez.html).

Impalas (Aepycerotini) are a particularly interesting tribe of bovids, combining a superficially deer-like appearance with multifaceted peculiarities (https://www.inaturalist.org/posts/89229-an-index-to-my-posts-about-the-impala-aepyceros-melampus#). They seem cover-dependent, but actually conform in various ways to 'plains game'.

Accordingly, impalas amble:

The bovid Kobus defassa is comparable in body size and shape to the cervid Cervus canadensis. However, the former is more likely than the latter to amble (https://front.motionarray.com/stock-video/common-waterbuck-walking-between-trees-1179445/ and https://www.alamy.com/stock-photo-walking-african-waterbuck-in-wild-78946808.html).

By contrast to many bovids, no cervid normally ambles. The semi cross-walk is retained by even those species showing certain adaptations associated with 'plains game', such as

  • long-range migrations (e.g. Rangifer tarandus),
  • lateral vision and wide-set orbits (e.g. Cervus elaphus),
  • bold colouration on the hindquarters (e.g. Dama dama, Odocoileus hemionus hemionus)

Masculine display in the rutting season does not involve a modification of gaits in Cervus elaphus, Cervus canadensis, and Elaphurus davidianus. These species 'strut' by semi cross-walking, not ambling.

Dama dama is, by contrast, versatile. In its 'strutting', this species adopts an amble under some circumstances, and a cross-walk under other circumstances..

Also see https://www.inaturalist.org/posts/84799-a-comparison-of-postures-and-gaits-between-two-elands-the-moose-alces-alces-and-the-common-eland-taurotragus-oryx#

Posted on March 30, 2024 04:51 AM by milewski milewski

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