rising@zoo.toronto.edu (Jim Rising) (06/12/91)
We need some input from a geneticist here, but my understanding was that the deleterious effects of inbreeding essentially disappear after 4-5 generations. There are lots of wild populations of animals that--doubtless as a consequence of having been bottle- necked--have essentially no genetic variation that seem to be doing all right, e.g. northern elephant-seal, cheetah. One would guess that there is very little variation in things like the whooping crane. I'm not saying that genetic variation isn't "a good thing," but if your parrots are always sickly maybe it has something to do with their captive situation (the food, or what have you). This does not strike me as an obvious a priori argument to capture wild birds the enhance the captive breeding populations. At least, let's get some input from geneticists about how best to do this before we jump on that bandwagon: how many new birds are needed to achieve the desired effect? what is the desired effect? how do we best breed the birds? etc? Weren't all present domestic hamsters descended from a single gravid female? Is our goal to have "healthy and happy pets" or to preserve genetic variation in wild populations? (I realize that there may soon be no wild populations of some of these species.) -- Name: Jim Rising Mail: Dept. Zoology, Univ. Toronto, Toronto, Ontario, Canada M5S 1A1 UUCP: uunet!attcan!utzoo!rising BITNET: rising@zoo.utoronto.ca
stewartw@cognos.UUCP (Stewart Winter) (06/13/91)
In article <1991Jun12.131020.22423@zoo.toronto.edu> rising@zoo.toronto.edu (Jim Rising) writes: >We need some input from a geneticist here, but my understanding >was that the deleterious effects of inbreeding essentially >disappear after 4-5 generations. I've not heard this before, so I'm open to possibilities. I would have thought that inbred birds could become substantially more likely to be wiped out by a disease. For example, some wild parrots exhibit natural resistance to PBFD, while most do not. If this were a genetic trait ... I'd be most curious too about possible adverse affects on reproductive rates induced by inbreeding extensively. Also, I know that the Loridae and Amazonia consortiums are quite concerned about maintaining genetic diversity. These groups have many 'knowledgeable' individuals in them. These organizations are both going to the trouble of using genetic 'fingerprinting' to determine how best to avoid inbreeding there birds. Maybe I jumped to a bad conclusion. >There are lots of wild populations >of animals that--doubtless as a consequence of having been bottle- >necked--have essentially no genetic variation that seem to be doing >all right, e.g. northern elephant-seal, cheetah. One would guess >that there is very little variation in things like the whooping >crane. Valid Point. >I'm not saying that genetic variation isn't "a good thing," >but if your parrots are always sickly maybe it has something to do >with their captive situation (the food, or what have you). I only had one pair of Princess of Wales (if it's my previous comments your refering too) and they were housed in a large flight (they could fly) and had a good diet. My observation was really more based on the fact that every Princess of Wales I have seen in captivity (with ONE exception) has had the same less-than-healthy appearance. >This >does not strike me as an obvious a priori argument to capture wild >birds the enhance the captive breeding populations. At least, >let's get some input from geneticists about how best to do this >before we jump on that bandwagon: how many new birds are needed >to achieve the desired effect? what is the desired effect? how do >we best breed the birds? etc? Agreed ... I'm not suggesting we strip every bird out of it's natural environment and put it in a cage ... far from that, but if a total ban is coming in 5 years do we have time to find out the importance of genetic diversity? > Weren't all present domestic hamsters descended from a single gravid female? >Is our goal to have "healthy and happy pets" or to preserve genetic variation >in wild populations? I think both are important and both are possible. >(I realize that there may soon be no wild populations of some of these >species.) Yes, and it's not just parrots. North American songbirds are much less well populated that 30 years ago ... it's the same story around the world. I think it would be really nice if aviculturalists could do something of value, but it's difficult to know what the best approachs to such a big problem are. It seems to me that the POSSIBILITY of something good exists, when we have a 'hobby' and an 'industry' that could be acting in the longterm interests of wildlife management. This is one area where conservationists can really contribute by not outright condemming the pet trade, but rather saying 'we would support if it was managed in the following way.' Stewart -- Stewart Winter Cognos Incorporated S-mail: P.O. Box 9707 VOICE: (613) 738-1338 x3830 FAX: (613) 738-0002 3755 Riverside Drive UUCP: stewartw%cognos.uucp@ccs.carleton.ca Ottawa, Ontario The bird of the day is .... Green-Cheeked Conure CANADA K1G 3Z4
kdb@intercon.com (Kurt Baumann) (06/13/91)
In article <1991Jun12.131020.22423@zoo.toronto.edu>, rising@zoo.toronto.edu (Jim Rising) writes: > I'm not saying that genetic variation isn't "a good thing," > but if your parrots are always sickly maybe it has something to do > with their captive situation (the food, or what have you). This > does not strike me as an obvious a priori argument to capture wild > birds the enhance the captive breeding populations. At least, Obviously not written by anyone who has every breed birds. Look, the situation is that the bigger the gene pool the better. If for example we bring in 400 pairs of Moluccan Cockatoos and over 5 years (it takes on average about 4-5 years to get a wild caught pair to breed) only 50 pairs produce chicks, then we obviously end up with a gene pool only consisting of those 50 pairs. The way things are working now those other 350 pairs may never breed. The reasons for why there is not a good rate are many, and not entirely understood. (More field research is needed, but there is no time..) But if for example every 2 years another 100 pairs were brought in and checked for health (better than what is currently done), NOT medicated out the wazoo, and in general treated better (perhaps 1 or two pairs per crate instead of the 50-100 birds per crate now (which is only one reason why I am against continued imports of birds). I believe that this would bring up the production rate, and would in the long run relieve the threat that some of these species are under. As an aside, to successfully breed, you need to be feeding the absolute best diet that science knows about for parrots. So sickly chicks have little to do with food. Parrots will not breed in close quarters, they need room. So their situation has little to do with sickly chicks. Those factors have to do with sickly pairs, and good breeders do what is needed in order to insure that their birds are not only healthy, but have what they need to produce. After all most of these breeders have several thousands of dollars invested, not only in the birds themselves, but also in their facilities. The plan that I would like to see and am going to work for is basically: 1. Stop imports for the pet trade. Period. 2. Allow imports of birds for "certified" breeding centers, not just Zoo's. Zoo's have their place but they are mainly for people to go see animals at. Breeding Parrots just don't really work when people are streaming by (like at the National Zoo in DC where they have been trying to breed endangered Black Palms for the last several years in a small cage with people snapping flash pictures at them). It just doesn't work. 3. Lobby all countries who now allow no exports of Parrots to open up slightly for exporting birds to breeding centers around the world. Perhaps with some sort of pay back by getting young birds to release into the wild. Obviously this all takes money to manage. That's why you would also need some way of generating income from the birds brought into the country. Breeders for the most part would be more than willing to pay extra for pairs if they knew that they had been WELL taken care of on the way into the country. Money can be generate from this and from the sales of domestic breed baby birds. This solution is not complete, but it is better than just cutting off the imports of birds that will either die off entirely or be smuggled in anyway. The buying public is just not aware of what is going on either. > let's get some input from geneticists about how best to do this > before we jump on that bandwagon: how many new birds are needed > to achieve the desired effect? what is the desired effect? how do > we best breed the birds? etc? Weren't all present domestic hamsters > descended from a single gravid female? Is our goal to have "healthy > and happy pets" or to preserve genetic variation in wild populations? > (I realize that there may soon be no wild populations of some of these > species.) The goal as I see it is both. We need to have healthy domestic pets to deal with the demand that is being put on the wild populations, but we also need to provide essentially a Noah's Ark service for those species going out of existence. Hamsters breed far to readily and far to often to be equated with Parrots. The youngest most parrots breed is at about 5 years of age, with most older than that. If you start running averages, and numbers out into the future you see that within about 10 years not only will the wild population be gone for the most part, but the growth of the domestic population will fall off. New pairs setup today will not produce (on average) until five years from now. There is not enough production of domestic birds today to fullfil demand and to save birds back for future production and preservation. One example that I know is the Rose Breasted Cockatoo from Austrailia. This bird is not endangered, however it does illustrate some of the problems that I am talking about. This bird breeds fairly readily, ask anyone from Austrailia, but even so, here in the US, where new birds have not been brought into the country since (I think) 1960, there still are not very many breeding pairs. After Austrailia cut off exports we were left with whatever was in the coutry at the time. The prices (which is a good indication of how many are available) for these birds has remained high $3,500+. They are just now starting to get well established in breeding populations in the US. Had we been able to get a few pairs every so often I think that there would be a larger and more viable population of these birds in the US. There are other species of Austrailian birds that have died off in the US becuase of several factors, original population size being amoung them. Anyway I could go on about this for a while, the end picture is that to totally cut off imports is sticking our heads in the sand and hoping that the problem will go away. It won't. The Moluccan Cockatoo is under the dual pressures of habitat destruction and wide spread desease, in addition to capture for the pet trade. Unfortunatly for these birds (or fortunatly) part of their continued survival as a species rests in the hands of breeders around the world. I don't believe that we can stop ourselves from cutting down every tree in the world hence the rainforests will be gone within the next 10 years. With those gone the habitat of these birds is also gone. Do we help them survive, in the hope that we will wake up and start setting aside land as preserves, or do we just ignore the problem and go our own way. We aren't stopping the import of rainforest hardwood, oil taken from jungles, paper created with rainforest wood, etc... Yet something that we can help survive, we want to ignore. I feel that banning the importation of birds for the pet trade is a good idea. I don't feel that the ban should be total. Kurt Baumann 703.709.9890 InterCon Systems Corp. Creators of fine TCP/IP products for the Macintosh
christ@sci.ccny.cuny.edu (Chris Thompson) (06/15/91)
An Australian theoretical geneticist (Warren Ewens) has spent some
time talking about the problem of genetic variation, and minimum viable
population sizes. ("Minimum viable population" is the current hot catch-
phrase in conservation biology). Anyway, the problem here is that when you
want to calculate a minimum viable pop. size, you DON'T use the actual
population size. You have to include the effective population size. I don't
recall the formula offhand, but it has to do with sex ratios, and the number
of animals that actually breed, and survival rates. Now, this can obviously
all be manipulated with captive populations, but still, the effective
population size is always much smaller than the actual population size.
Also, there has always been this mystique associated with the number
500. This has been bandied about as a standard minimum viable population
size---below 500, most species will not maintain enough genetic variation
to make it for more than about 50 years. Warren Ewens again (this was the
subject of a seminar he gave at Columbia University 1.5 years ago)
thouroughly debunked this notion, showing that the number is almost always
much greater than 500. His position was that the number 500 was based on a
series of "heroic assumptions", which werem't valid. So I don't think I'd
spend a lot of time trying to catch wild birds to maintain genetic
variation in captivity. I think I'd rather see it remain in wild
populations.
Chris Thompson
Biology Department, CCNY
--
"Never count a human dead until you've seen the body. And even
then you can make a mistake".
-Lady Fenringjday@spam.ua.oz (Jemery Day) (06/17/91)
In article <1991Jun15.154957.3243@sci.ccny.cuny.edu> christ@sci.ccny.cuny.edu (Chris Thompson) writes: > An Australian theoretical geneticist (Warren Ewens) has spent some >time talking about the problem of genetic variation, and minimum viable >population sizes. ("Minimum viable population" is the current hot catch- >phrase in conservation biology). Anyway, the problem here is that when you >want to calculate a minimum viable pop. size, you DON'T use the actual >population size. You have to include the effective population size. I don't >recall the formula offhand, but it has to do with sex ratios, and the number >of animals that actually breed, and survival rates. Now, this can obviously >all be manipulated with captive populations, but still, the effective >population size is always much smaller than the actual population size. Genetic variation is not the only consideration when trying to find a minimum viable population. The effects of demographic stochasticity - i.e. the chance nature of birth and death in a population; environmental stochasticity - i.e. random fluctuation in weather patterns with resulting in variation in the availability of food and water; and catastrophe - i.e. bushfire which can destroy food sources and habitat. All four factors are important in performing a population viability analysis on a given population. ("Population Viability Analysis" is also "hot" in conservation biology). > Also, there has always been this mystique associated with the number >500. This has been bandied about as a standard minimum viable population >size---below 500, most species will not maintain enough genetic variation >to make it for more than about 50 years. Warren Ewens again (this was the >subject of a seminar he gave at Columbia University 1.5 years ago) >thouroughly debunked this notion, showing that the number is almost always >much greater than 500. His position was that the number 500 was based on a >series of "heroic assumptions", which werem't valid. So I don't think I'd >spend a lot of time trying to catch wild birds to maintain genetic >variation in captivity. I think I'd rather see it remain in wild >populations. Population viability analysis is used to try to estimate the probability that a given population of a particular species will become extinct over a given time interval. The notion that a population larger than a particular magic number will be "safe" from extinction is complete rubbish. You can attempt to associate a probability with a given initial population, with that probability representing the chance that the population will become extinct over a given time interval (say 500 years). The point is that these processes are effected by chance events and as such must give results which can only be interpreted in terms of probabilities. In terms of maintaining genetic diversity and decreasing the chances of species extinctions I agree with Chris, leave the birds in wild populations! >Chris Thompson >Biology Department, CCNY Jemery Day Applied Mathematics Department Adelaide University
rim@csadfa.cs.adfa.oz.au (Bob McKay) (06/17/91)
From article <28577E6E.68B8@intercon.com>, by kdb@intercon.com (Kurt Baumann): > > 1. Stop imports for the pet trade. Period. > > 2. Allow imports of birds for "certified" breeding centers, not just Zoo's. > Zoo's have their place but they are mainly for people to go see animals at. > Breeding Parrots just don't really work when people are streaming by (like at > the National Zoo in DC where they have been trying to breed endangered Black > Palms for the last several years in a small cage with people snapping flash > pictures at them). It just doesn't work. > > 3. Lobby all countries who now allow no exports of Parrots to open up slightly > for exporting birds to breeding centers around the world. Perhaps with some > sort of pay back by getting young birds to release into the wild. This won't work, at least with cockatoos. If you keep them, then you must be aware of how intelligent and social they are. Released birds don't have the learned background to survive (and in the case of the flock species, they can't survive anyway without a flock, and they won't be allowed to join an existing flock). Pet sulphur crested cockatoos released or lost in Australia don't go out and survive in the wild, they just hang around cities trying to get their flock cousins (people) to look after them, and die when they don't succeed. > > This solution is not complete, but it is better than just cutting off the > imports of birds that will either die off entirely or be smuggled in anyway. > The buying public is just not aware of what is going on either. > The birds (at least the Australian ones) are mostly holding their own. The ban on exports of the common ones, say galahs, makes it that much harder to hide the rare ones that would otherwise be disguised in the exports of the common ones. It also drives up the price of the common ones, so that the smugglers concentrate more on them, and take a little pressure of the rare ones. Bob McKay Phone: +61 6 268 8169 fax: +61 6 268 8581 Dept. Computer Science ACSNET,CSNET: rim@csadfa.cs.adfa.oz Aust. Defence Force Academy UUCP: ...!uunet!munnari!csadfa.cs.adfa.oz!rim Canberra ACT 2600 AUSTRALIA ARPA: rim%csadfa.cs.adfa.oz@uunet.uu.net
ooblick@intercon.com (Mikki Barry) (06/18/91)
In article <1991Jun15.154957.3243@sci.ccny.cuny.edu>, christ@sci.ccny.cuny.edu (Chris Thompson) writes: > series of "heroic assumptions", which werem't valid. So I don't think I'd > spend a lot of time trying to catch wild birds to maintain genetic > variation in captivity. I think I'd rather see it remain in wild > populations. Making the assumption that the wild populations have a habitat to stay wild in. That is our major problem right now.
ooblick@intercon.com (Mikki Barry) (06/18/91)
In article <1991Jun17.024522.12693@sserve.cc.adfa.oz.au>, rim@csadfa.cs.adfa.oz.au (Bob McKay) writes: > This won't work, at least with cockatoos. If you keep them, then you must be > aware of how intelligent and social they are. Released birds don't have the > learned background to survive (and in the case of the flock species, they can't > survive anyway without a flock, and they won't be allowed to join an existing > flock). Pet sulphur crested cockatoos released or lost in Australia don't go out > and survive in the wild, they just hang around cities trying to get their flock > cousins (people) to look after them, and die when they don't succeed. You are making the assumption that the birds will be kept as pets before re- release. If the parents completely raise the cockatoos, they will be perfectly capable of returning to a wild population.
rim@csadfa.cs.adfa.oz.au (Bob McKay) (06/18/91)
From article <285D20D1.4189@intercon.com>, by ooblick@intercon.com (Mikki Barry): > In article <1991Jun17.024522.12693@sserve.cc.adfa.oz.au>, > rim@csadfa.cs.adfa.oz.au (Bob McKay) writes: >> This won't work, at least with cockatoos. If you keep them, then you must be >> aware of how intelligent and social they are. Released birds don't have the >> learned background to survive ...... >> .. Pet sulphur crested cockatoos released or lost in Australia don't go out >> and survive in the wild, they just hang around cities trying to get their >> flock cousins (people) to look after them, and die when they don't succeed. > > You are making the assumption that the birds will be kept as pets before re- > release. If the parents completely raise the cockatoos, they will be perfectly > capable of returning to a wild population. Of course not, the point is that the wild environment is so complex, and so different from what they are used to, that the birds can't possibly get the education they need just from being raised with their parents. They have truly enormous home ranges, migrating many hundreds of kilometres each year, and the migration paths are complex, as the food sources for some are rare, and their locations have to be memorised. You are underestimating the intelligence of your pets and the complexity of the environment that they have evolved to cope with if you think that they can learn all that from their caged parents (or perhaps you're overestimating them, and believe that the parents can communicate it all verbally 8-)). It seems to take a young cockatoo years - perhaps five or more - to fully learn all the skills it needs to survive in the wild; how could cage learning ever possibly substitute for that? Bob McKay Phone: +61 6 268 8169 fax: +61 6 268 8581 Dept. Computer Science ACSNET,CSNET: rim@csadfa.cs.adfa.oz Aust. Defence Force Academy UUCP: ...!uunet!munnari!csadfa.cs.adfa.oz!rim Canberra ACT 2600 AUSTRALIA ARPA: rim%csadfa.cs.adfa.oz@uunet.uu.net
ooblick@intercon.com (Mikki Barry) (06/19/91)
In article <1991Jun18.090020.24510@sserve.cc.adfa.oz.au>, rim@csadfa.cs.adfa.oz.au (Bob McKay) writes: > Of course not, the point is that the wild environment is so complex, and so > different from what they are used to, that the birds can't possibly get the > education they need just from being raised with their parents. They have truly > enormous home ranges, migrating many hundreds of kilometres each year, and the > migration paths are complex, as the food sources for some are rare, and their > locations have to be memorised. You are underestimating the intelligence of your > pets and the complexity of the environment that they have evolved to cope with > if you think that they can learn all that from their caged parents (or perhaps > you're overestimating them, and believe that the parents can communicate it all > verbally 8-)). It seems to take a young cockatoo years - perhaps five or more - > to fully learn all the skills it needs to survive in the wild; how could cage > learning ever possibly substitute for that? I am going by the observation that captive bred macaws have been parent raised and re-released into the wild with complete success. Cockatoos and macaws have comparable intelligence levels. I am not underestimating their intelligence by any means. I have seen my one pet and many breeder cockatoos use tools, solve puzzles, etc. etc.