The mule deer and the damalisk: a paradox of stotters

Both the Rocky Mountain mule deer (Odocoileus hemionus, https://www.inaturalist.org/observations?taxon_id=143865) and damalisks (Damaliscus spp.) stot.

However, the former stots so frequently, consistently, and persistently that there are many illustrations of this demonstrative gait (https://www.youtube.com/watch?v=h8DweS5Z684 and https://www.youtube.com/watch?v=v1_qLKWeXPA) on the Web.

By contrast, the latter stot so seldom that, after trawling through tens of thousands of photos and videos, I have found only one photo (https://stock.adobe.com/images/a-beautiful-topi-antelope-in-the-mara-grassland/62749286?prev_url=detail).

This difference is puzzling.

Indeed, it is doubly puzzling, for the following reasons.

Firstly, there is context.

Stotting - particularly in adults - is a reaction to the arrival of predators, particularly cursorial predators as opposed to ambush predators. The mule deer is usually photographed in situations where the wolf (Canis lupus) has long been exterminated, meaning that the gait is in reaction to the photographer.

By contrast, Damaliscus lunatus (https://www.inaturalist.org/taxa/42276-Damaliscus-lunatus) is often photographed in conservation areas replete with various Carnivora. This means that there is a good chance of photographing it reacting to the arrival of the African hunting dog (Lycaon pictus, https://www.inaturalist.org/taxa/42093-Lycaon-pictus).

Secondly, there is phylogeny.

The mule deer is congeneric - and partly sympatric - with the white-tailed deer (Odocoileus virginianus), which never stots in the strict sense (https://www.inaturalist.org/posts/89498-gaits-and-anti-predator-displays-compared-between-deer-odocoileus-in-north-america-and-impalas-aepyceros-in-africa#).

By contrast, damalisks are related to the red hartebeest (Alcelaphus caama), which has fairly frequently been photographed stotting in adulthood in reaction to human approach ().

In the case of the blesbok and bontebok (Damaliscus pygargus), there are two possible reasons why there are no photos of adults stotting, viz.

• stotting is naturally absent in this species (possibly because this species is adapted for conservation of energy in nutrient-poor environments), or
• none of the current populations are subject to the natural regime of predation, particularly w.r.t. the African hunting dog.

In the common impala (Aepyceros melampus), playful rehearsing of the kick-stotting gait is not restricted to juveniles, but occurs also in adult females. This kind of extended playfulness seems not to apply to damalisks.

The above disparities raise a strange thought, as follows.

We have succeeded in saving the bontebok from extinction. The blesbok has actually been restored to a kind of semi-domesticated abundance. However, a certain behaviour is now 'extinct' in these antelopes.

Nowhere is it practicable, today, for these taxa to coexist with the African hunting dog, let alone the full original community of predators. This is unlikely to be remedied in future.

Hence, generation after generation of these damalisks may continue indefinitely without ever expressing a certain natural gait in adults.

If so, one way to think of this plight is as follows.

Imagine a species of acacia which has been saved from extinction only in a few botanical gardens. It happens to have a capacity for spinescence. However, this 'induced defence' is expressed phenotypically only after a certain kind of damage - plus the associated saliva - by a particular herbivore. For practical ('hormonal') reasons, this damage is not emulated artificially.

Thus, generation after generation, the species continues to exist without manifesting something that was, in the original condition, an important part of its nature.

Also see:
https://www.inaturalist.org/posts/89452-stotting#
https://www.inaturalist.org/posts/76632-stotting-in-damaliscus#
https://www.inaturalist.org/posts/70294-one-of-the-few-records-of-stotting-in-hippotragin-bovids#
https://www.inaturalist.org/journal/milewski/80713-the-mara-dolichotis-patagonum-the-most-ungulate-like-rodent-on-earth#
https://www.inaturalist.org/journal/milewski/archives/2022/09#
https://www.inaturalist.org/journal/milewski/90651-illustrations-of-stotting-gaits-in-cervine-deer-cervidae-cervinae#
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#
https://www.inaturalist.org/posts/49366-locomotory-and-postural-peculiarities-of-impalas-aepyceros-part-1#
https://www.inaturalist.org/posts/71185-the-ten-most-important-differences-between-alcelaphus-cokii-and-alcelaphus-caama#activity_comment_e0236539-4e0b-4861-9530-1120346de1c8#

Publicado el marzo 27, 2024 10:02 TARDE por milewski