Puzzling parallel evolution between African hunting dog and spotted hyena, despite different life history strategies
(writing in progress)
In some ways the spotted hyena (Crocuta crocuta) has a different life history strategy from the African hunting dog (Lycaon pictus).
The former lives long, breeds slowly, and achieves a kind of constancy demographically. The latter lives short, breeds fast, and has great fluctuations in its population, partly because it is far more susceptible to epidemics (e.g. distemper) than the spotted hyena is.
At the same time the spotted hyena and hunting dog, although both gregarious, have different approaches to cooperation among individuals. The former has an essentially selfish approach in which there is no paternal care and even among females the offspring depends on her mother alone. In the African hunting dog the father is a devoted provider.
The gender roles are also different: in the spotted hyena the emphasis is on females, whereas in the hunting dog the groups are actually composed more of males than of females.
As part of these differences, the spotted hyena relies on milk far more than does the hunting dog, which tends to bring back solid food (by mouth of by regurgitation) and weans its offspring early.
Given these divergences, it is intriguing that the colouration of the two carnivores is so similar. It is this that I’d like to explore in the following photos. I’ve never seen these parallels in colouration pointed out as such in the literature, let alone explained.
Of course it is obvious to the lay person that there is a similarity in appearance between spotted hyena and African hunting dog (to the degree that ignorant people actually confuse the two species), but the details are interesting.
To summarise the puzzle in a way that I think is quite original (i.e. I’ve never seen this in the literature):
Both the spotted hyena and the hunting dog show the same basic puzzle of colouration. This is why the overall colouration has disruptive ‘spotting’ in animals that cannot really use this camouflage in their hunting because their hunting methods are incompatible with freezing or hiding, and their use of the tail flag makes them so conspicuous.
Not only has it never been explained how these carnivores use camouflage, but it has certainly never been explained why they have converged in their pattern of ‘camouflage’. I can only imagine that there are times when the animals must freeze in terror (e.g. when attacked by the lion), possibly at night when this behavioural reaction has not been observed, and at those critical times the camouflage can make all the difference between death and survival).
I have never seen ‘freezing’ behaviour recorded for either the spotted hyena or the African hunting dog but unless it occurs in some way then the idea that these species are camouflaged makes little sense, would you not agree?
Both the spotted hyena and the African hunting dog have somewhat spotted coats, a dark mask, a neck-flag, and a tail flag.
The following photos illustrate all these features in the hunting dog. In neither species is the somewhat spotted coat easy to explain adaptively, because spots are associated with disruptive (inconspicuous) colouration and because both of these carnivores hunt by moving in the open they cannot be using camouflage in their hunting.
My point is that in both the spotted hyena and the African hunting dog, the somewhat spotted pattern of the coat (mainly on the body) – which after all is the main feature of the colouration in both species - remains an adaptive puzzle.
Both the spotted hyena and the hunting dog have dark masks. This is hard to interpret because, although one might reason that dark masks help to make an approaching predator inconspicuous, in fact the spotted felids such as leopard and cheetah do not have dark masks.
So the dark masks are in one sense part of the same puzzle as the somewhat spotted coats (the puzzle being how cursorial as opposed to stalking hunters could possibly make use of camouflage) but in another sense constitute a separate puzzle.
Many and diverse Carnivora have dark masks and it’s hard to see what is in common among all of them. The dark mask is more consistent among living hyenids than among the various taxa of Canidae, and so it seems that the hunting dog has for some reason converged with hyenas w.r.t. its dark mask. To what end?
http://farm3.static.flickr.com/2776/4099690001_31156c5a74.jpg
Both the spotted hyena and the hunting dog have neck flags, which I’ve never seen pointed out in the literature in either case. In both cases this flag consists of a pale panel on the side of the neck, which is largely free of the spots found elsewhere on the coat.
A difference is that in the spotted hyena the pale panel is located more ventrally whereas in the hunting dog it is situated more dorsally; and in the hunting dog there is a tonal constrast with the ventral surface of the neck which tends to be dark (much as in the striped hyena).
One difference is that in the spotted hyena the spotting and neck flag are most visible in adolescents, tending to fade with full maturity, whereas in the hunting dog these features persist in fully mature individuals.
Although one could quibble about details my overall point is that the markings on the neck of the hunting dog are remarkably hyena-like (and I can’t think offhand of another canid that matches this). To what end? Is there some sort of mimicry going on, given that the lion also has a similar neck-flag in the case of the female and adolescent male?
One nuance which I am sure has never been pointed out before: the dull fawn of the dorsal surface of the neck is actually similar in the two species (the spotted hyena having a desultory but erectile crest consisting of dull fawn hairs).
However, in the spotted hyena this dorsal pelage on the neck is hardly noticeable owing to its similarity to the ground-colour, whereas in the hunting dog the fawn panel on the dorsal surface of the neck tends to stand out in conjunction with the fawn of the temple area of the face.
http://cdn.c.photoshelter.com/img-get2/I0000huNUwUmC9z8/fit=1000x750/SAF-7078c.jpg
Both the spotted hyena and the African hunting dog have conspicuous tails because the tail tassels show tonal contrast the tails are readily erected in excitement. In both species, a conspicuous erect tail is normal during activity, and in both species the tail flag is certainly the premier conspicuous feature of the whole appearance.
Most coexisting large carnivores, including lion, leopard and cheetah (although apparently not brown or striped hyena) also have tail flags, but the display of the tail flag is extreme in both spotted hyena and hunting dog because the tail is so readily erected for so much of the time.
One difference of detail is that in the spotted hyena the main tone of the tail tassel is dark, whereas in the hunting dog the main tone is pale. I.e. the spotted hyena basically has a dark-tasselled tail (with a rather pale band more proximally) whereas the hunting dog basically has a white-tasselled tail (with a dark band more proximally).
https://spottedtrails.files.wordpress.com/2014/09/shingwedzi-08aug-116-edit-logo-fb.jpg
The spotted hyena has approximately double the body mass of the African hunting dog.
https://s-media-cache-ak0.pinimg.com/736x/76/dd/9c/76dd9c496b69ff2a22c755cfeb2b67a0.jpg
(writing in progress)
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