Differences among gazelles in the structure and function of the tail

No standard terms have been established to compare the tails among ungulates. Here, I use 'shaft' to mean the flesh-and-bone structure, and 'tassel' to mean the long hairs concentrated distally. 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. I assume that all species swish the tail to shoo insects.

In Gazella, the tail is simple in structure but demonstrative in function. 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). The tail is wagged and raised during walking and trotting, but is held in the fully upright position in non-stotting flight only in Gazella subgutturosa and Gazella marica. The latter two species are odd also in possessing, on the sides of the base of the shaft, pale fringes of fur which can be piloerected (see https://www.flickr.com/photos/144908175@N07/40226721515/).

In Nanger, the tail is simple and undemonstrative, even during stotting. The tassel is small, and in Nanger dama almost absent (see https://pixels.com/featured/1-addra-gazelle-ncz-17-1-robert-michaud.html).

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

In Antilope, the fur on the tail tapers to a point excluding any dark tassel. Apart from erection during some bouts of stotting (see https://www.gettyimages.com.au/detail/video/blackbuck-antelope-pronks-on-grassland-velavadar-stock-video-footage/918318364?adppopup=true), the tail is undemonstrative - the anomaly being masculine display, when it is held 'hypererected' to the degree of being turned upside-down.

Antidorcas and Litocranius have similarly tapering shafts ending in similarly dark, small tassels. However, in the former the shaft is whitish (see https://www.istockphoto.com/photo/protective-mom-and-baby-springbok-stare-back-in-the-desert-gm160377111-22791345) and the tassel is piloerected while the tail is inert, whereas in the latter the shaft is dark and the tassel is never piloerected (see https://stock.adobe.com/search?k=gerenuk&asset_id=30423210). The stotting displays are extremely different, but in neither genus is the tail demonstrative; in the stotting springbok the tail is redundant in view of the flared white fur on the rump and buttocks.

In Ammodorcas, the dark tail is particularly noticeable because it is longer than in any other gazelle, and erected during flight. This genus is ecologically similar to Litocranius but surprisingly different in the form and function of the tail.

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. Thomson's gazelle (Eudorcas thomsoni) has a reputation for doing the latter, but 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 http://www.blaircostelloe.com/research/thomsons-gazelles/preventing-predation-of-neonates/).

Publicado por milewski milewski, 16 de junio de 2021


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

Publicado por milewski hace alrededor de 1 año (Marca)

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