Adaptive colouration in the blesbok (Damaliscus pygargus phillipsi), part 2: infants, juveniles, and adolescents

...continued from

The blesbok has uniform pale colouration at birth, which differs categorically from that of adults.

In juveniles of Damaliscus pygargus, the facial colouration is the inverse of that of adulthood, with the facial bleeze beginning dark, and the adjacent cheeks beginning pale ( and

INFANTS (birth to three months old, including first appearance of horns)

The colouration of infants of the blesbok is categorically different from that of adults.

The ground-colour (including the posterior surfaces of the ear pinnae) is pale, with countershading. The countershading includes the ventral surface of the neck.

The tail-tassel is merely incipient.

The only distinct pattern is seen on the face, where the ground-colour of the rostrum and upper lips is crisply separated from whitish cheeks. Whitish extends on to the orbits except for the anterior side of the orbits ( and and

This is, in a sense, the opposite pattern from that in adults (

There is also

The maximum body size reached by offspring within the infantile colouration is shown in and the second photo in At this stage the weight of infant/juvenile is about one quarter of maternal weight.


3-6 months old:

The rostrum, and to lesser degree the upper foreleg, abruptly turn dark (

This produces a temporary 'inverse' version of the facial bleeze.

The following, of adult female and juvenile (?4.5 months old) of the blesbok, is one of the clearest illustrations of the conspicuous facial pattern suddenly adopted by juveniles, after three months of infantile colouration. This conspicuous pattern is the inverse of the adult pattern, in that the rostrum is dark while the cheeks are pale:

About eight months old (see ):

Whitish hairs appear on the rostrum, creeping upwards from the nose. Countershading disappears from the neck.

8-12 months old:

At about one year old, pale appears on the forehead (individually variable). The rostrum (now pale) and tail-tassel (dark since birth) remain proportionately shorter than in adults.

ADOLESCENTS (1-2 years old, see

Among the last features to form fully is the whitish patch on the forehead.

ADULTS (>2 years old, see

Fully mature adults:



I have noticed then following tentative differences, which depend on further photographic evidence for verification:

Perhaps the most significant finding:

Juveniles, 3-6 months old, have more conspicuous facial colouration in the blesbok than in the bontebok. This is the inverse of the relationship between these two taxa in adulthood, at the scale of the whole figure.

This unexpected difference hints that the blesbok and the bontebok are actually different species, not merely subspecies of the same species.

Also see

For an index to my many Posts about the genus Damaliscus, please see

Publicado el marzo 4, 2023 12:11 MAÑANA por milewski milewski


The first photo in shows two juvenile individuals more than six months old, in the same green season as their birth, in a part of South Africa with a long rainy season.

The adult female individual is probably older than seven years, judging from the expansion of pale pelage on the cheeks and muzzle.

After more than six months of growth, juveniles have outgrown the stage of a dark rostrum and pale cheeks. Their rostrum is starting to turn pale.

Please note that juveniles of this age resemble adults in lacking any countershading on the neck.

Publicado por milewski hace alrededor de 1 año

The following, of the blesbok, shows both the size attained within the stage of infantile colouration (at about three months old) and the auricular flag of adults:

Publicado por milewski hace alrededor de 1 año
Publicado por milewski hace alrededor de 1 año

The following shows that, at about eight months old, the ischiopygal flag is fully-developed, despite the face being at the stage of dark rostrum and pale cheeks:

Publicado por milewski hace alrededor de 1 año

Two juvenile individuals, 1-2 years of, of the blesbok, showing the following points: a) the pale patch on the forehead is one of the last features to appear, b) there is individual variation in this respect, c) a trace remains of the pale streak of juveniles, posterior to the eyes.

Publicado por milewski hace alrededor de 1 año

The following ( contains two video-clips of the blesbok.

These illustrate, inter alia:

a) Newborns, with their conspicuously pale colouration, both close-up and at some distance.

b) Bearing in mind the seasonal reproduction of the blesbok: the appearance of one-year old juveniles and two-year old adolescents in the same group.

c) The nodding display, which seems more pronounced than in the bontebok, and may help to explain the presence of an auricular flag in the blesbok particularly.

Publicado por milewski hace alrededor de 1 año
Publicado por milewski hace alrededor de 1 año


Meissner H H (1976) A note on the energy requirements of young, growing blesbok. South African Journal of Wildlife Research 6(1): 51-53.

According to this reference, infants and juveniles of the blesbok have the following mean body masses according to age (sex not specified):

15 days 7.1 kg

32 days 9.0 kg

95 days 15.4 kg

184 days 24.2 kg

337 days 31.6 kg

504 days 46.9 kg

My commentary:

Infants of the blesbok more than double their body mass in about three months (I infer that newborns weigh 6.5 kg, and infants of 3 months weigh 14.5 kg). They then double their body mass again over the next 7.7 months. At the age of about 17 months, body mass is about 72% of maternal body mass (assuming that adult females average 65 kg).

Publicado por milewski hace alrededor de 1 año

The following is my description of the colouration of the blesbok at about 7 months old:

The colouration is nebulous at this stage, transitional between the relatively graphic colouration of 3-6 months old and that of adults.

None of the dark surfaces of adulthood are fully-expressed yet. In the case of the tail-tassel, the darkness is complete, but the tassel remains only half-size.

The pale (whitish) surfaces are already fully-expressed on the buttocks, abdomen, and lower legs.

This means that the abdominal, ischiopygal, pedal, and probably auricular flags are relatively precocial, whereas the facial bleeze is tardy. The ulnar flag is not as precocial as the functionally associated abdominal flag, because the dark on the posterior surface of the upper foreleg is tardy.

The main distinctive pattern of juveniles 3-6 months old, viz. the dark/pale contrast on the face, is already lost. If any dark/pale contrast remains on the face, this is because the pelage between the eyes remains dark, whereas that on the temples, and to a lesser degree that on the forehead, remains more-or-less pale.

The pelage on the anterior parts of the mandibles remains pale. The countershading on the ventral surface of the neck remains only near the crook-of-throat.

However, the adult facial pattern is still far from apparent.

The conversion of the rostral patch from dark to pale has begun on the distal part, near the rhinarium.

The patch on the forehead changes from dark to pale with relative tardiness. However, this is individually variable.

Publicado por milewski hace alrededor de 1 año
Publicado por milewski hace alrededor de 1 año
Publicado por milewski hace alrededor de 1 año

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