A new observation on gaits in the maternal defensive behaviour in the moose (Alces alces)

Has anyone previously observed the following anomaly in the gaits of the moose (Alces alces, https://www.inaturalist.org/taxa/522193-Alces-alces)?
 
What I have noticed is that, under certain circumstances, Alces alces performs a ‘perfect cross-walk’, a gait extremely unusual among ungulates. (See http://www.carscoops.com/2013/08/mamma-moose-throws-road-rage-temper.html.)
 
Long-legged ungulates typically walk by means of a gait called an amble, in which the limbs on one side (left or right) tend to move together, followed by the limbs on the other side.

This is in contrast to a cross-walk, used by certain mammals, such as baboons (https://www.alamy.com/chacma-baboon-walking-along-the-road-near-the-cape-of-good-hope-cape-point-route-south-africa-image218671095.html) and the aardvark (https://www.expertafrica.com/wildlife/aardvark/africa).

In a cross-walk, front left and hind right are moved in synchrony, followed by front right with hind left.

This is essentially a ‘primitive’ walking gait, associated with salamanders (https://www.dkfindout.com/us/animals-and-nature/amphibians/how-salamander-moves/), lizards (https://www.alamy.com/bengal-monitor-lizard-varanus-bengalensis-wilpattu-national-park-sri-lanka-walking-image341526746.html), and tortoises.

By contrast, there is the amble:

This is instead associated with many mammals.

The amble is epitomised by giraffes (https://www.youtube.com/watch?v=Vh2yveXTKaU). However, it seems to be the normal gait of even mammals as short-legged as echidnas (https://www.dreamstime.com/short-beaked-echidna-australian-walking-image189271677).
 
Alces alces is unusual for a long-legged ungulate, in normally using a walking gait that I call a 'semi cross-walk'. In this way it resembles forest antelopes, rather than ‘plains game’.

As an informative digression:

Few ruminants normally use a cross-walk, e.g. Capreolus and Oreotragus (https://www.inaturalist.org/taxa/42384-Oreotragus-oreotragus). The latter is extremely adapted for stability in rocky terrain (https://www.istockphoto.com/photo/klipspringer-ewe-oreotragus-oreotragus-walking-gm1166459730-321336832 and https://www.alamy.com/male-klipspringer-oreotragus-oreotragus-a-dry-country-antelope-with-thick-coat-walking-on-tip-toe-on-rocky-lava-in-tsavo-west-np-kenyaafrica-image241664074.html and https://www.alamy.com/male-klipspringer-oreotragus-oreotragus-a-dry-country-antelope-with-thick-coat-walking-on-tip-toe-on-rocky-lava-in-tsavo-west-np-kenyaafrica-image241664075.html).

Compare Oreotragus with Raphicerus campestris of similar body size and limb length: https://www.alamy.com/stock-photo-steenbok-raphicerus-campestris-walking-south-africa-krueger-national-76132028.html.

Among ungulates, a cross-walk is epitomised by Hippopotamus amphibius (which not only has relatively short legs, but is only marginally unguligrade).

Returning to Alces alces:

This large-bodied deer usually semi cross-walks, as opposed to ambling.

This may perhaps be partly explained partly by

• obstructive habitat, consisting mainly of forest and water-bodies,
• adaptation for stability in deep snow, or on ice and mud,
• adaptation for stepping over obstacles, such as fallen logs, and
• a short neck, distinguishing Alces alces from those long-legged ruminants that seem to use their long necks as a kind of cantilever while walking.

However, under at least one circumstance unrelated to deep snow or obstruction, Alces alces actually resorts to a 'perfect' cross-walk: http://www.carscoops.com/2013/08/mamma-moose-throws-road-rage-temper.html.

The following (http://a57.foxnews.com/global.fncstatic.com/static/managed/img/fn2/video/876/493/edge_moose_052014.jpg?ve=1&tl=1) shows the typical walking gait of Alces alces.

I have categorised this as a semi cross-walk. However, it could alternatively be described as a gait intermediate between cross-walk and amble, but more on the side of a cross-walk than on the side of an amble.

The diagnostic feature is the fact, clearly illustrated here, that the hind foot is lifted BEFORE the opposite fore foot is planted.
 
The following (http://c8.alamy.com/comp/EY5DAH/guanaco-walking-amble-argentina-EY5DAH.jpg) shows Llama guanicoe (https://www.inaturalist.org/taxa/42240-Lama-guanicoe), as an example of the general tendency among long-legged ungulates to use an amble as the walking gait.

In an amble, the hind foot is lifted only after the opposite fore foot is planted. This gait applies to other camelids, as well as giraffes and 'plains game' antelopes.

Even certain plantigrade - as opposed to unguligrade - mammals, such as Ursus maritimus (https://videohive.net/item/polar-bear-walking-in-an-arctic/31377836 and https://www.mirror.co.uk/news/world-news/lost-polar-bear-strolls-around-16535338), walk with a gait closer to an amble than that of Alces alces.

The following (https://i.ytimg.com/vi/c00CoAKBAb4/maxresdefault.jpg) shows that Hippopotamus amphibius (https://www.inaturalist.org/taxa/42149-Hippopotamus-amphibius) use a 'perfect' cross-walk.

This is exceptional among ungulates, and can be explained by

• a mainly aquatic habitat,
• adaptation for stability on slippery ground,
• shortness of the legs, and
• the fact that hippos are the least unguligrade (https://en.wikipedia.org/wiki/Digitigrade#/media/File:Les_diff%C3%A9rents_types_de_locomotions_chez_les_amniotes.png) of all ungulates.

The temporary but 'perfect' cross-walk to which our mother of Alces alces resorts in defence of its twins (http://www.carscoops.com/2013/08/mamma-moose-throws-road-rage-temper.html) can alternatively be thought of as a slowed-down version of the trot (https://en.wikipedia.org/wiki/Trot).

The trot is the most common running gait of Alces alces.

In this instance, it does not qualify as a trot, because the locomotion is so slow that there is never a moment when all four feet are in the air. Instead, at all times there are two feet on the ground, which defines this gait as a walk. However, the associated stability seems to apply.

This adoption of a 'perfect' cross walk by Alces alces cannot be explained by a slippery surface. This is because this tar road in summer seems dry and firm.

It may perhaps be part of the defensive display, accentuated by a raised withers-mane and lowered ears. However, such subtlety is hard to evaluate, without more experience of how Alces alces behaves.
 
The following (https://www.dreamstime.com/royalty-free-stock-images-angry-moose-image14554269) shows another individual of Alces alces, photographed separately, adopting a less intense defensive posture while walking. What we see here is merely the normal intermediate gait, viz. a semi cross-walk.

My interpretion of the circumstance in question:
When defending her infants, this mother Alces alces adopted a gait of maximal stability, allowing her to change gait (e.g. in charging) as rapidly as possible. This cross-walk allows the animal to retreat from the intruder, while at the same time being able to turn sharply, to defend her progeny.

It would be interesting to see whether certain other long-legged ruminants, such as Taurotragus (https://www.inaturalist.org/taxa/75192-Tragelaphus-oryx), also adopt a perfect cross-walk when in full defensive mode. I suspect that nobody has previously had a search-image for this.

Also see https://www.inaturalist.org/journal/milewski/67632-locomotory-and-postural-peculiarities-of-the-impala-part-2#.

Posted on August 23, 2022 11:38 PM by milewski