Differences among gazelles in the structure and function of the tail

In this Post, I make preliminary comparisons among Gazella, Nanger, Eudorcas, Antilope, Antidorcas, Litocranius, Ammodorcas, and Procapra, with respect to the tail as an adaptive organ.

I assume that all species swish the tail to shoo insects. As far as I know, no gazelle, in stationary alarm, either holds the tail erect (as seen in certain species of deer) or wags the tail nervously. However, other demonstrations by means of the tail are surprisingly diverse.

Please note that

  • no standard terms have been established to compare the tails among ungulates;
  • I use 'shaft' to mean the flesh-and-bone structure, and 'tassel' to mean the long hairs concentrated distally; and
  • in all gazelles, the ventral surface of the tail is bare skin.

I refer only to adults; the tail tends to be most demonstrative in infants.

Gazella:

In Gazella, the tail is simple in structure but demonstrative in function, as follows.

The tassel is bushy and dark, and covers most of the shaft (see https://www.dreamstime.com/stock-photo-mountain-gazelle-walking-field-israel-image91922790).

In Gazella, the tail is wagged and raised during walking and trotting.

The tail is held in the fully upright position, in non-stotting flight, only in

The latter two species are odd also in possessing, on the sides of the base of the shaft, pale fringes of hair which can be piloerected (see https://www.flickr.com/photos/144908175@N07/40226721515/).

Nanger:

In Nanger, the tail is simple and undemonstrative, even during stotting (https://nationalzoo.si.edu/animals/dama-gazelle).

In this genus, the tassel is small, and in Nanger dama almost absent (see https://pixels.com/featured/1-addra-gazelle-ncz-17-1-robert-michaud.html).

Eudorcas:

In Eudorcas, the tail is proportionately larger than in Gazella, and demonstrative.

However, the main demonstration is wagging during nervous, intermittent walking.

Once the animal runs, the tail tends to be relaxed (see https://www.agefotostock.com/age/en/details-photo/thomson-s-gazelle-male-running-gazella-thomsoni/MEV-10763890).

Many naturalists may have the impression that Thomson's gazelle (Eudorcas thomsoni) wags the tail while stationary.

However, careful observation shows that the tail is activated only once a leg moves (see video in https://dissolve.com/video/Thomson-Gazelles-Blue-Wildebeest-Mara-River-Maasai-Mara-rights-managed-stock-video-footage/002-D806-133-014 and https://www.youtube.com/watch?v=LPfG028yzpI and https://www.dreamstime.com/gazelle-herd-wagging-their-tails-serengeti-gazelle-herd-wagging-their-tails-serengeti-national-park-tanzania-video216825150).

Antilope:

In Antilope, the fur on the tail tapers to a point excluding any dark tassel.

The tail in Antilope is undemonstrative, apart from erection during some bouts of stotting (https://www.gettyimages.com.au/detail/video/blackbuck-antelope-pronks-on-grassland-velavadar-stock-video-footage/918318364?adppopup=true and https://www.alamy.com/black-bucks-are-resident-species-of-gujarat-india-and-are-found-in-many-places-these-are-found-in-big-groups-and-doing-jumping-and-running-all-day-image359843002.html?imageid=59E8E834-332A-49CE-B096-7063CC504E1F&p=676501&pn=1&searchId=3c49af6cb8a3a05fe8eb462ea3360571&searchtype=0 and https://www.alamy.com/black-bucks-are-resident-species-of-gujarat-india-and-are-found-in-many-places-these-are-found-in-big-groups-and-doing-jumping-and-running-all-day-image359843063.html?imageid=2E159E96-68A4-4276-997E-3EA0F27CAE46&p=676501&pn=1&searchId=3c49af6cb8a3a05fe8eb462ea3360571&searchtype=0).

The anomaly in Antilope is masculine display, in which the tail is held 'hypererected', to the degree of being turned 'upside-down' (https://www.inaturalist.org/posts/47421-surprising-differences-in-displays-of-the-tail-between-the-blackbuck-and-other-gazelles#).

Antidorcas and Litocranius:

Antidorcas and Litocranius resemble each other in having similarly tapering shafts, ending in similarly dark, small tassels.

However,

The stotting displays of Antidorcas and Litocranius are extremely different.

However, in neither case is the tail demonstrative. When Antidorcas stots (https://www.youtube.com/watch?v=jMIiB9DnRXg), the tail seems redundant, in view of the flared white pelage on the rump and buttocks.

Ammodorcas:

Ammodorcas is ecologically similar to Litocranius, but surprisingly different in the form and function of the tail.

The dark tail is particularly noticeable (https://uk.inaturalist.org/taxa/42272-Ammodorcas-clarkei). This is because it is

  • longer than in any other gazelle, and
  • erected during fleeing.

Procapra:

Finally, we have the genus Procapra (see https://www.inaturalist.org/journal/milewski/69383-adaptive-colouration-in-procapra#), which is anatomically at the other extreme from Ammodorcas in terms of the length of the tail.

The tail is too short in Procapra to warrant coverage in this Post.

Posted on Ιούνιος 16, 2021 0136 ΜΜ by milewski milewski

Σχόλια

One of the clearest photos of the tail of Nanger granti notata is https://www.flickr.com/photos/gmaquedaphotos/49146496358.

Αναρτήθηκε από milewski περίπου 3 χρόνια πριν

Hand-raised adult male Eudorcas thomsoni, stotting playfully, and showing caudal flag: https://www.youtube.com/watch?v=KzP6mDZeM9c.

Αναρτήθηκε από milewski σχεδόν 2 χρόνια πριν

https://www.inaturalist.org/observations/148095417

This is the clearest illustration I have yet seen of the subtle differentiation in length of the white pelage on the buttocks of Gazella dorcas, the longer hair being piloerected (flared) in alarm, as part of caudal flagging.

Αναρτήθηκε από milewski 9 ημέρες πριν

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