How the intelligence of the smallest duikers helps to explain their behaviour

Duikers (cephalophin bovids) are brainier than other ruminants (see https://www.researchgate.net/profile/Lynette-Hart/publication/285056929_Duiker_behavior/links/565b7d1608aefe619b243cce/Duiker-behavior.pdf).

This may help to explain why the blue duiker (Philantomba monticola) is so diurnal, so playful, so family-minded, so deceiving in certain ways, and so specialised for 'mutual kissing' by means of both the tongue and the glandular cheeks.

Play behaviour in adulthood is generally associated with intelligent species. Ungulates tend to have about average braininess for mammals, and accordingly play in infancy but not in adulthood.

Duikers are exceptions to this, and in the case of the blue duiker adult males are particularly playful (e.g. see video in https://wdef.com/2020/07/30/chattanooga-zoo-gets-blue-duikers/ and caption to https://www.instagram.com/p/CDreN_BDMvo/).

Several kinds of small ruminants besides the blue duiker are monogamous for life, but this species has slow reproduction relative to its body size, and is unusually tolerant of juveniles remaining in the natal territory after sexual maturity. This presumably gives the offspring opportunities to learn from the experience of their parents, which is typical of primates rather than ungulates.

Females, although married, are like all ungulates in allowing copulation only at the peak of oestrus. In the face of an impatient husband, females of the blue duiker sometimes use a deceptive tactic of distraction: they 'cry wolf' using a whistle that is otherwise used only as an anti-predator alarm.

The blue duiker is the prime example of allogrooming in bovids, and perhaps in all ruminants. The tongue is far longer than can be explained in terms of foraging (see https://www.alamy.com/a-blue-duiker-philantomba-monticola-with-its-tongue-out-whilst-feeding-at-cango-wildlife-ranch-image179075434.html), and is used to lick a partner's fur in surprisingly frequent and extensive bouts of reciprocal grooming (see https://www.youtube.com/watch?v=Swe0gEvZjuY and https://www.naturepl.com/stock-photo-blue-duiker-philantomba-cephalophus-monticola-allogrooming-mlilwane-image01297865.html).

This intimate behaviour aids familial bonding and exceeds what can be explained by hygiene and removal of ticks. It seems analogous to mutual grooming in monkeys.

The blue duiker has a large maxillary gland running along each cheek (see http://blog.phantomforest.com/2012/09/blue-duiker/ and https://wildimagesinmotion.com/blue-duiker-close-up/). Whereas most bovids use the facial glands mainly for masculine marking of the territory, the blue duiker is odd in the extent to which the animals scent-mark each other's bodies, with females reciprocating fully.

What is more, the mutual anointing extends to simultaneous pressing of the glands to each other, thus mixing secretions. This is similar to the human 'cheek-kiss' but far more intimate. And, most surprisingly, rival males mutually cheek-press their glands together before fighting violently, in what is more like a gentlemanly 'handshake before duelling'.

Posted by milewski milewski, July 05, 2021 12:36

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Most naturalists would agree that 'cute' is an apt adjective for the blue duiker, but it may be doubly apt. This is because the original meaning was 'clever', 'cunning' or 'shrewd', rather than endearing in an infantile way (see https://www.bing.com/search?q=define+cute&form=ANNTH1&refig=ae5334ee582444e499b2aeea68e8eb40). The word-origin is 'acute', i.e. mentally sharp. The blue duiker is cute in both ways.

Posted by milewski over 1 year ago (Flag)

Intriguing read. May I ask, are there any cases of male parental care for offspring in Philantomba cephalophins?

Posted by gingko_biloboa1 11 months ago (Flag)

@gingko_biloboa1

Hi Michael, many thanks for your question. I searched for 'parental care' and 'paternal care' in duikers on Google scholar. The only relevant information is in the paper linked below. In Table 2 the authors show no paternal care in duikers and in the text they mention that there is paternal care in tne sense of anti-predator vigilance. On page 7 of http://aloki.hu/pdf/1202_505521.pdf the authors state that there is no parental care in Philantomba monticola, but I think this is a typographical error and they meant paternal.

Philantomba may differ from other cephalophins but I do not know of any recent research. I trust that this helps.

https://www.sciencedirect.com/science/article/abs/pii/S0006320708004916

https://www.researchgate.net/profile/Danielle-Brown-27/publication/223441143_Animal_breeding_systems_and_big_game_hunting_Models_and_application/links/5ef76939a6fdcc4ca433d9bc/Animal-breeding-systems-and-big-game-hunting-Models-and-application.pdf

Posted by milewski 11 months ago (Flag)

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