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Sterile Ferals - Yes/No?
My sister and I have recently decided to try a semi-vegetarian lifestyle - we'd only eat meat on weekends. This has nothing to do with us being squeamish about eating dead things (I used to finger paint with blood samples in biology class after all), but more an attempt to save money and improve our health. I don't know if you've noticed but, depending on what and where you buy it, meat can be quite expensive. We started talking about why different types of meat were priced differently in different states. For example, my sister mentioned that our mum bought some kangaroo meat in country Victoria for almost double what it would cost here in Adelaide. I told her that feral kangaroos were a big problem in northern South Australia, and the fact that hunters could (legally) go on a killing spree at certain times of the year probably accounted for the abundance and lower price of kangaroo meat here.
But this got me to thinking about feral animals in general. Feral animals are a big problem here in Australia, especially introduced species such as rabbits and foxes - they threaten the balance of our ecosystem and the environment's ability to regenerate properly. Every year scientists and governments try to come up with new ways to limit feral populations. Their most recent idea is fertility control, either through viruses, chemicals, or surgical removal of reproductive organs.
When choosing to implement ANY wildlife management strategy, however, we have to take into consideration all the underlying factors – target species, risks, effectiveness, locality etc.
In the case of introduced feral species, they don’t seem to warrant the same concerns about humane treatment as do many of our native species. Most people want to aim for drastic (if not complete) population reduction and want the most effective method possible. I believe this is where hunting comes into play. There is no denying the effectiveness of a good old bullet to the head - in a large focus area where the aim is eradication rather than limitation (e.g. rabbits and foxes), the time and cost involved in trapping, anesthetics, surgery and re-release are unrealistic and unnecessary.
I don’t believe in the use of viral methods to cull feral populations because I feel they’re nowhere near as effective. With the introduction of the myxoma virus in the wild rabbit population, they were seeking a long term solution that would spread quickly and not require much continued effort. At first it seemed to be successful and large numbers of rabbits died, but like a common cold in humans, the rabbits soon built up immunity and the virus became redundant. Now scientists constantly have to come up with new strains of myxoma to try and combat this. This is going to happen with any viral strains they try to introduce (not to mention it’s difficult to control the geographical spread), so other methods should be considered first.
When considering overpopulation in our native species, we’re usually looking at a small, localized focus area, and this is where I feel fertility control (more specifically, immuno-sterilization) is the best method. In this case, we need to consider the target species in order to develop the best plan of action - is the species a seasonal or year-round breeder; is it monogamous or polygamous; is it monoestrus or multiestrus; and does it need a specific vegetation, temperature, or landscape to be successful in reproduction? Each of these factors may impact the effectiveness of a particular infertility agent. Many suggest surgical sterilization (vasectomy/hysterectomy), but this is often an irreversible and stressful procedure for an animal and greatly limits the gene pool. Chemical fertility management is a flexible tool that permits a large variety of control and can be tailored to specific species.
In a study by Kirkpatrick et al. (1982), they reported a successful inhibition of reproduction in feral horses by lowering sperm counts in stallions. A micro-encapsulated form of testosterone propionate was injected into stallions several months before breeding season. The poly (DL-lactide) coating permitted a sustained release, thereby causing impairment of sperm mobility for up to six months. This left the stallions’ behaviour unaffected and breeding still took place, but there was an 83% reduction in foals produced. This method could sustain a release of contraceptive steroids for years with just one injection if developed properly. This ensures that animal behaviour and interaction is unaffected, and treatments could easily be reversed if populations drop below safe levels. It also means that the gene pool remains intact.
Depending on the size of the animal, baits or even tranquilizer darts could be used to administer the chemicals, thus removing the need for human interaction. Now, delivering bait to a particular species without having other animals ingest it is near impossible, but by tailoring drug type and dosage, effects on non-target species can be minimized. Moreover, the peak breeding season differs between species, making it easier to deliver drugged bait to a target group.
I’m not saying that there aren’t risks involved with immuno-sterilization, because there are. But I believe, with further research, and if used properly in conjunction with other methods, it can become a very effective means of population control (and will keep the public happy over animal cruelty concerns).
Next step: limiting the interference and ecological tampering of humans.
References
* Fagerstone, K.A. et al. (2002). “Wildlife Fertility Control”, http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1484&context=icwdm_usdanwrc
* Kirkpatrick, Jay F.; Turner, John W. Jr. (1985). “Chemical Fertility Control and Wildlife Management”. BioScience, 35 (8), pp. 485-491.
* Oogjes, Glenys (1997). “Ethical aspects and dilemmas of fertility control of
unwanted wildlife: an animal welfarist’s perspective”. Reproduction, Fertility and Development, 9 (1), pp. 163–7.
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What are your thoughts on wildlife management and control? I'd love to hear them :)
Dimi's Random Thought For The Day: Sometimes I think humans should be considered a feral species. I've met a number of people who should DEFINITELY be prohibited from breeding.
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But this got me to thinking about feral animals in general. Feral animals are a big problem here in Australia, especially introduced species such as rabbits and foxes - they threaten the balance of our ecosystem and the environment's ability to regenerate properly. Every year scientists and governments try to come up with new ways to limit feral populations. Their most recent idea is fertility control, either through viruses, chemicals, or surgical removal of reproductive organs.
When choosing to implement ANY wildlife management strategy, however, we have to take into consideration all the underlying factors – target species, risks, effectiveness, locality etc.
In the case of introduced feral species, they don’t seem to warrant the same concerns about humane treatment as do many of our native species. Most people want to aim for drastic (if not complete) population reduction and want the most effective method possible. I believe this is where hunting comes into play. There is no denying the effectiveness of a good old bullet to the head - in a large focus area where the aim is eradication rather than limitation (e.g. rabbits and foxes), the time and cost involved in trapping, anesthetics, surgery and re-release are unrealistic and unnecessary.
I don’t believe in the use of viral methods to cull feral populations because I feel they’re nowhere near as effective. With the introduction of the myxoma virus in the wild rabbit population, they were seeking a long term solution that would spread quickly and not require much continued effort. At first it seemed to be successful and large numbers of rabbits died, but like a common cold in humans, the rabbits soon built up immunity and the virus became redundant. Now scientists constantly have to come up with new strains of myxoma to try and combat this. This is going to happen with any viral strains they try to introduce (not to mention it’s difficult to control the geographical spread), so other methods should be considered first.
When considering overpopulation in our native species, we’re usually looking at a small, localized focus area, and this is where I feel fertility control (more specifically, immuno-sterilization) is the best method. In this case, we need to consider the target species in order to develop the best plan of action - is the species a seasonal or year-round breeder; is it monogamous or polygamous; is it monoestrus or multiestrus; and does it need a specific vegetation, temperature, or landscape to be successful in reproduction? Each of these factors may impact the effectiveness of a particular infertility agent. Many suggest surgical sterilization (vasectomy/hysterectomy), but this is often an irreversible and stressful procedure for an animal and greatly limits the gene pool. Chemical fertility management is a flexible tool that permits a large variety of control and can be tailored to specific species.
In a study by Kirkpatrick et al. (1982), they reported a successful inhibition of reproduction in feral horses by lowering sperm counts in stallions. A micro-encapsulated form of testosterone propionate was injected into stallions several months before breeding season. The poly (DL-lactide) coating permitted a sustained release, thereby causing impairment of sperm mobility for up to six months. This left the stallions’ behaviour unaffected and breeding still took place, but there was an 83% reduction in foals produced. This method could sustain a release of contraceptive steroids for years with just one injection if developed properly. This ensures that animal behaviour and interaction is unaffected, and treatments could easily be reversed if populations drop below safe levels. It also means that the gene pool remains intact.
Depending on the size of the animal, baits or even tranquilizer darts could be used to administer the chemicals, thus removing the need for human interaction. Now, delivering bait to a particular species without having other animals ingest it is near impossible, but by tailoring drug type and dosage, effects on non-target species can be minimized. Moreover, the peak breeding season differs between species, making it easier to deliver drugged bait to a target group.
I’m not saying that there aren’t risks involved with immuno-sterilization, because there are. But I believe, with further research, and if used properly in conjunction with other methods, it can become a very effective means of population control (and will keep the public happy over animal cruelty concerns).
Next step: limiting the interference and ecological tampering of humans.
References
* Fagerstone, K.A. et al. (2002). “Wildlife Fertility Control”, http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1484&context=icwdm_usdanwrc
* Kirkpatrick, Jay F.; Turner, John W. Jr. (1985). “Chemical Fertility Control and Wildlife Management”. BioScience, 35 (8), pp. 485-491.
* Oogjes, Glenys (1997). “Ethical aspects and dilemmas of fertility control of
unwanted wildlife: an animal welfarist’s perspective”. Reproduction, Fertility and Development, 9 (1), pp. 163–7.
-
What are your thoughts on wildlife management and control? I'd love to hear them :)
Dimi's Random Thought For The Day: Sometimes I think humans should be considered a feral species. I've met a number of people who should DEFINITELY be prohibited from breeding.
-
no subject
A very interesting article on population control and culling.
My own reasons for turning vegetarian was not so much the PETA reason (Oh the inconsistencies I could raise aout PETA~) but simply a palleted one. xD I dislike the texture and taste of meat lol.
After taking all possabilities into consideration I do beleive that limiting the sperm count is probably the best way to do things.
Spreading viruses seems to be a short term solution (It's scary how many of these are around today) and could endanger the health of any other native animal that may through some circumstance or another contract it.
It's a shame we just cant hire some sort of piped piper type character to sort the problem out ;D
This post reminds me of this shirt design by Kate Beaton lol