Some captive chimpanzees seem to loose there hair or great patches off it - is it pulled out from fighting or is it more of a nervous thing
There is also the "naked" chimps, I believe that these are chocolate coloured chimps that loose their hair as they grow until they are bald? Maybe some others can elaborate on this?
As Taun said, its mainly two pronged with the reasons he says. Stress leads to self-plucking- this is quite common in gorillas but not sure with chimps which are less prone to stress in captivity due to their less nervous disposition. So I think it is usually the result of over-grooming from other chimps. (If it occurs in a solitary chimp it could again be due to self-grooming rather than plucking.) Bonobos seem particularly prone to this, particularly on the head and arms. I used to think it was plucking due to nervous dispositions, but have been told its mainly overgrooming, perhaps the result of their highly social natures. The completely bald male Chimps at Twycross are(or rather were!) both chocolate-coloured ones- whether their baldness is genetically linked to their colour/sex or there is a different explanation seems debatable. There are chocolate females that aren't bald, but there again, the two males concerned are also brothers.
Does this baldness not occur in the wild? I remember poor old Rodney (my all time fav. zoo animal) of MW fame, and he was sort of comically bald.
Never seen it in any films of Chimps, or in the real-life ones at Gombe which have thick black coats. With wild Bonobos, their fur is very black and shiny, with the characteristic tufts over the ears. I would think overgroomng is a product of captivity what with all that spare time not required in searching for food.
I think Rodney was just an old boy but interesting you bring that up his succesor Hanaya and his group are a prime example .
I watched a film recently that featured Bonobos in Africa- there were the familiar bald heads and bare arms on some(not all) of them. Then I realised-they weren't wild- it was a controlled environment, some type of rescue place where they would have been fed artificially. I think its purely a product of captivity.
Don't forget that the eastern race of chimps, found at Gombe Stream, is known as the long-haired chimpanzee: although I think there is a good deal of individual variation in all the races and of course in wild individuals the health and nutrition of the individual also matters. Otherwise I agree with Pertinax about hair plucking in captive apes. I can't recall seeing anything similar in orangs, except perhaps for infants with over-attentive mothers. It can happen in mandrills too, Chester's old male (JC) who is quite highly strung, has bare patches on his arms. Alan
I'm not sure if I've ever seen a case of hair plucking in an Orangutan. In the bad old days of concrete surfaces and floors of cages, it was common to see semi-baldness in Orangs, particularly in juveniles, but that was caused by the hair being rubbed off on hard surfaces- primarily on the back and thighs. Hair of adults seems somehow to be more resilient. There are exceptions though e.g. the Blackpool female Victoria has very bare arms- maybe from plucking? The male Mandrill at Chester is the only one I've seen with arms like that- I always presumed he plucks them rather than being groomed to create that appearance.
It is a complicated subject. In many cases, plucking has become a habit, almost a culture. An animal has learned it in a zoo or rescue center, and will learn it to her/his cage mates or infants. So the zoo where the animals are being plucked cannot always be blamed, they just might have received a plucker. A good example is this bonobo rescue center in the DRC, which is Lola ya Bonobo. They have some rescued animals that spent many years in small cages of a research institute. They started plucking in that institute, and continued with it in Lola, even though the animal live there in large groups and large enclosures. In some cases it is also caused by the low humidity of the enclosure, therefore in some zoos we see bigger problems during the winter, when the animals are often inside. There might also be a connection with feeding to much fruits, but that needs further investigation.
That would be the place I mentioned above. They were in semi-natural conditions. Another species that seems prone to overgrooming is the Red-capped Mangabey. The red head seems the main focus and grooming/plucking is confined mainly to that. Most groups I've seen contain at least some monkeys with semi-bald crowns. Again, as most of the European groups contain some animals transferred from other groups, the spread of the habit could occur that way. Again I attribute it to the fact the animals spend far more time engaged in social grooming in captivity than in the wild.
Hananya's group at Monkey World are very patchy and there is some thought that it is a result of a large number of them being reared to some extent by Sally, a very keen groomer. Kiki came with completely bare arms from plucking when she was in a tiny cage for years. It sometimes seems to improve in the summer when they are getting out more. Thankfully the baby Thelma seems to have avoided this so far. Paddy's group are far less prone to this. The chimps currently in Sally's group seem less affected. The adolescent males Ben in the bachelors and Bryan in Sally's group are magnificent young chimps with fantastic hair!
