Do zoo animals have it too easy?

[Arizona Docent]

Someone made a comment on another thread about large mixed species field exhibits not being as conducive to breeding (for hoofstock) as large single species exhibits (due to inter-species agression). This reminded me of a thought I have had before, but never vocalized. Do animals need a certain amount of natural stressors for their well being? In other words, are we in the zoo world making animal's lives too easy and taking away their edge? Are we creating breeds of pseudo-domestic animals. Are we making it impossible for them to ever be reintroduced to the wild?

 

[cleusk]

In other words, are we in the zoo world making animal's lives too easy and taking away their edge?

Free food, free housing, free healthcare, plenty of friends . . . I wouldn't complain.

 

[TARZAN]

Free food, free housing, free healthcare, plenty of friends . . . I wouldn't complain.

Fair comment, but on the other hand what about being boxed up and taken away from your friends and family one day, on stud book recommendations, for the good of the captive breeding programme of the species concerned, but what does the actual individual animal think when he/she is in the back of a van or a lorry being driven away to join other animals that they have never met before?, or to be kept alone as they are not compatible with the animals that live at their new abode?,

 

[nanoboy]

Free food, free housing, free healthcare, plenty of friends . . . I wouldn't complain.

My tax payer dollars are paying for a few facilities like that at the moment.

 

[chrisbarela]

The idea of natural stress as a breeding stimulation is one of the theories why the San Diego Safari Park has had so many successes. The fact that the hoofstock can hear and smell the lions (and probably coyotes and cougars as well) may play a key part in their breeding.

 

[Hix]

Stress has been used as a behavioural enrichment device. Rotating different species through cages can cause them to become alert when they discover new smells, and then investigate them. Even a keeper entering an enclosure to clean it can cause stress for some animals, and this can also be classed as an enrichment. Obviously, only low levels of stress should be employed.

Do animals need a certain amount of natural stressors for their well being?

Stress causes an increase in adrenaline. Prey species escaping from a predator pump a lot of adrenaline.

In other words, are we in the zoo world making animal's lives too easy and taking away their edge? Are we creating breeds of pseudo-domestic animals. Are we making it impossible for them to ever be reintroduced to the wild?

A concept was introduced some years ago called 'genetic selection for captivity'. The idea goes like this:

A population of a species that is naturally shy and skittish is brought into captivity. Some of the more highly-strung individuals don't cope with living in zoos and die off in the first few months. The remaining individuals don't thrive, but survive in captivity, described as 'difficult species to keep'. A few breed, some of the offspring are very nervous, others are a bit calmer. The calmer ones breed more than the nervous ones, and over time the population ends up favouring animals that, although wary of keepers and visitors, are not as nervous and highly strung as the wild animals. While this is good for captive management, it is definitely not good for reintroduction as it is very possible the very nervous trait was essential for the individual's survival in the wild.

And it makes you wonder - what other traits are there that we can't readily see, that we are breeding out of the captive populations?



Hix

 

[Vulpes]

I have often thought about the effects of captive breeding over long periods of time on wild animals. It is inevitable that there will be some domestication, despite the stud book keepers best efforts. The animals that adapt best to captivity will thrive and breed, those that are somewhat amenable to human contact and that can adapt to the stresses associated with this. Those that don't die and don't reproduce, therefore over a long period of time, change will take place. also with changing natural habitats in the wild the wild ancestors will be changing also. Evolution is not something that is ever finished. It happens every day so perhaps captive animals will be left behind as their wild counterparts adapt and change along with their environments. That's the way it works after all!

 

[Vulpes]

We have already seen from the silver fox experiments in Russia, simply breeding from the "friendliest" i.e. less aggressive and calmest of specimens results in genetic changes, such as piebald coats and curly tails. I think this could apply to any captive animal. The foxes only took 40 generations. I'm sure some captive lion and tiger lines have well passed that by now!

 

[Pertinax]

or to be kept alone as they are not compatible with the animals that live at their new abode?,

I wonder who you are thinking of.....

My particular dislike in this area is when Zoos have to remove e.g. a male Gorilla from a breeding group and to cover it they say it is natural for them to leave or to live in all male groups. Neither is correct,at least where it involves healthy mature males, though this practise is increasingly becoming a necessary facet of captive management.

The animal I felt sorriest for was the breeding male Gorilla 'Motaba' at Melbourne Zoo- when he was removed from the group he had lead for a number of years on genetic grounds, he was kept on his own adjacently and within sight of his erstwhile group. I imagine that was extremely stressful for him. He has since been relocated with his sons to their open range zoo at Werribee, which is at least an improvement.

 

[IanRRobinson]

Does the predominance of male births that certain species held in captivity seem to have (Asian Elephants and Gaur at Whipsnade spring immediately to mind, and Gorillas seemingly everywhere) maybe spring from having such a rich diet?

Well-fed females are able to carry bigger offspring - which tend to be male. Does anyone have any thoughts?

 

[Vulpes]

Does the predominance of male births that certain species held in captivity seem to have (Asian Elephants and Gaur at Whipsnade spring immediately to mind, and Gorillas seemingly everywhere) maybe spring from having such a rich diet?

Well-fed females are able to carry bigger offspring - which tend to be male. Does anyone have any thoughts?

I have heard a theory that stress can cause high instances of male births, the theory being that male animals tend to roam further from their birth place than females, away from the stressful conditions.

Pygmy Hippos are another good example of high male births.

Sex is determined by the father in all mammals possessing the XY chromosomes, so a well fed female would not really influence the off-springs sex.

Is there a higher instance of male births among birds reptiles etc also?

 

[Pootle]

Does the predominance of male births that certain species held in captivity seem to have (Asian Elephants and Gaur at Whipsnade spring immediately to mind, and Gorillas seemingly everywhere) maybe spring from having such a rich diet?

Well-fed females are able to carry bigger offspring - which tend to be male. Does anyone have any thoughts?

Hey Ian,

It’s an interesting thought, however I look at it like this;

The Asian Elephant and Gaur births at Whipsnade despite being predominately male (all male in the Gaur is it?) are still way too low in numbers of births to give any scientific data to prove any hypothesis, I believe you would need 100’s of births to prove this, which would mean much much bigger populations and a good number of different bull elephants ‘having a go’ and a large herd (ideally herds) of females to give birth. Same for the Gaur too.
Also in mammals I believe that after about six(ish) weeks of pregnancy the sex of the offspring has been determined, (some mammals with shorter gestation periods may have this determined earlier) and at this stage it is so small that its sex would not be a factor in the size of the mother.

However because we are dealing here with what is virtually individual examples rather than populations of a species, it may be a specific genetic trait to an individual, ie the bull male here favours the XY chromosome over the XX chromosome, this could be due to a minor genetic mutation, again this opens another can of worms that are only theories. Loads of theories can be put forward, but without the high number of births (at least 100’s, ideally 1000’s), nothing specific can really be proved apart from an individuals breeding record.

 

[lintworm]

@Vulpes, I once did some research on the genetic influence of captivity on the animals. Examples with butterflies (Pieris) showed that the animals that came from a 50 year old captive stock were significantly heavier, but had less muscle mass and were less fast. Similar examples are also found in Drosophila and in captive Salmon, where the salmon really had a very low reproductive success when originating from a salmon farm.

But that is no surprise, as you take away many parameters where animals should adapt to, because there is no need to be the fastest or most energy efficient individual. And very slowly that will become visible in species that have been in captivity for many generations.

But the 3 studies cited all used captive animals that had little space etc. but I think the result will be the same for other animals, with more space.

 

[Pootle]

Is there a higher instance of male births among birds reptiles etc also?

I know nothing about birds, so that is easliy answered!

However with in Crocodilian species temperature can govern the sex of a hatchling, so up the temp a notch or two for female and even drop a notch or two for female, where as male is a steady set temp......or is it the other way round , either way its more like baking a type of cake than determining mammal sexes .

 

[Vulpes]

Also in mammals I believe that after about six(ish) weeks of pregnancy the sex of the offspring has been determined, (some mammals with shorter gestation periods may have this determined earlier) and at this stage it is so small that its sex would not be a factor in the size of the mother.

Sex is determined at conception!

 

[Vulpes]

I know nothing about birds, so that is easliy answered!

However with in Crocodilian species temperature can govern the sex of a hatchling, so up the temp a notch or two for female and even drop a notch or two for female, where as male is a steady set temp......or is it the other way round , either way its more like baking a type of cake than determining mammal sexes .

I forgot about this! From wikipedia:

"If the temperature inside the nest is below 31.7°C (89.1°F), or above 34.5°C (94.1°F), the offspring will be female. Males can only be born if the temperature is within that narrow range."

Birds I think have a ZW chromosome and sex is determined differently, so I guess that answers my question thanks!

 

[Dassie rat]

I often get asked if zoos are cruel for animals. Basically, it depends on the zoo and the species. Some species seem to adapt better to captivity than others and, as other Zoochatters have pointed out, some individuals have short lives in captivity, while others thrive and are protected from many causes of stress that they would face in the wild, as well as having a healthy diet and veterinary care. This means that life may be too easy for them and they would have problems surviving in the wild.

In fact, there are many zoos that have no intention in returning some of their animals to the wild. There was a debate a few months ago about Damian Aspinall sending gorillas back to Africa, although there were still problems with people killing gorillas. In many cases, there is insufficient habitat for large animals that have high captive populations.

This is why I feel that zoos should co-ordinate which species they keep, especially those that are not being bred to replenish wild populations. Large species with total captive populations in the hundreds and thousands are being promoted at the expense of smaller species that could be bred and reintroduced in the wild. Unfortunately, some of the smaller animals are rarer than some of the more familiar ones and could soon become extinct due to habitat destruction and the lack of interest from most conservationists.

 

[Pertinax]

Yes, I think that though it is tempting to seek a reason, when several calves in a row are all male, the bigger picture might present a very different outcome.

The skewed sex ratios in some zoobred species has always been a well known problem. But its not always in favour of males. In Pygmy Hippo births females predominate, while its the same for Spix Macaw, a species one might assume has been(at least till recently) heavily stressed under captive conditions.

I remember London in the 1960-80's period used to have a breeding group of Pigtail Macaques, and here again, they produced almost all one sex(male) offspring, to the degree it starts to invite speculation as to the cause. Male babies are very common and inceasingly 'inconvenient'(for their Zoo management) in Gorillas too, though there have been some zoos where there have been fortuitous 'runs' of female babies, which tend to balance out the overall picture.

 

[Pootle]

Sex is determined at conception!

Yes, more dodgy wording from Pootle! I should have described it as the sex characteristics be it male or female are defined after this time. Sex is of course as you say fixed at point of conception.

 

[tschandler71]

Isn't the idea behind this thread one of the driving points of rotational exhibits?