Surprising variation in infantile colouration in gazelles

All gazelles and other antilopin bovids hide their newborns for at least one week, during which the infant lies as low as possible. Because these antelopes live in relatively open vegetation, concealment of infants depends partly on inconspicuous colouration.

In the gerenuk (Litocranius walleri), the gazelle most likely to hide by means of inconspicuous colouration, it is unsurprising that the infant has virtually identical colouration to the adult. However, those species which have conspicuous colouration in adults vary surprisingly in the patterns of infants. Take, for example, Thomson's gazelle (Eudorcas thomsoni, see and the western dama gazelle (Nanger dama mhorr, see The former has a striking contrast between the dark flank-band and tail and the adjacent pale surfaces, while the latter has conspicuous white on the rump, lower flanks, upper legs and face.

The infant of Thomson's gazelle (see and has colouration similar to that of the adult, the conspicuous markings being suppressed to some extent by posture, body-proportions and the relative length of the fur. By contrast, the infant of the western dama gazelle (see is so different that, were it observed in isolation, one could scarcely tell which species - or even genus - it belongs to.

The adults of neither species make much attempt to hide. What differs is that the conspicuous features are already present at birth in Thomson's gazelle whereas they are not in the western dama gazelle. Particularly odd is that the infant of the western dama gazelle lacks most of the pale on the hindquarters, in contrast to Thomson's and other gazelles, in which erectile white fur on the buttocks is precocial. In both species, the tail is most conspicuous in the infant, and frequently erected in excitement. However, the difference is that in the infant of the western dama gazelle the only conspicuous feature on the whole figure is the white mid-section of the tail. White becomes conspicuous on its buttocks only when the infant grows into a juvenile.

Publicado el mayo 29, 2021 06:45 MAÑANA por milewski milewski


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