Wild Animals/Kangaroo Culling

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Question
I am doing a research paper on kangaroo population control in Australia, specifically the Eastern and Western Grey and Red. I have two questions. My questions are:
Do you believe there is a viable means of introducing birth control to kangaroos in the wild?
Culling is currently used extensively. It seems this is the most effective and efficient means of controlling population with their grasslands shrinking and population growing.  What are your thoughts on culling as a means of kangaroo population control in Australia?

Thank you for your time and thoughts regarding my questions.

Answer
Dear Nate

Thank you for your questions. I also wish to thank the authors of the websites I used. Please note that I have tried to edit the two papers, but you may need to check the biochmical details expressed in the first one.

Birth control: Catherine Herbert wrote a paper (http://www.awrc.org.au/uploads/5/8/6/6/5866843/catherineherbert.pdf) about using birth control. Suprelorin is a long-acting contraceptive implant, containing the gonadotrophin-releasing hormone (GnRH) agonist deslorelin. This implant inhibits reproduction in female eastern grey kangaroos by shutting down the production of hormones from the pituitary. This inhibits follicular development and disrupts oestrous cycles, so females are in a permanent state of anoestrus whilst the implant releases its active ingredients. Contraception tends to last about 18 months with no negative behavioural side-effects. As the implant is injected by had, the kangaroos must be captured. If kangaroos have become habituated to people, they are relatively easy to capture using immobilisation drugs injected from a pole syringe. If kangaroos have had little interaction with humans or have negative interactions with humans, it can be very difficult to get near enough to safely try to dart animals, making the exercise prohibitively expensive.
As fertility control does not involve removal of adult animals, it can take some time before there is a decline in the population. when the mortality rate exceeds the birth rate within the population. If kangaroos are captured, they may become more wary in future. There has been work on developing a prototype dart to facilitate remote delivery of the Suprelorin contraceptive implant, which will reduce the cost of administering individual implants.

Birth control seems to be a good idea and has been found to control populations of various kangaroos and wallabies.

Culling: High populations of large herbivores in various countries is often linked to the rarity of suitable predators. In a natural predator-prey balance, the predators tend to choose weak and elderly prey, leading to the survival of stronger individuals. Hunters often choose the stronger animals, which provide better trophies or skins, hence weakening populations. Unfortunately, people have helped wipe out large predators in Australia and have introduced animals that compete with, or help to wipe out, native animals.

David Croft (http://www.awpc.org.au/kangaroos/bias.htm) notes that Queensland tends to cull large male kangaroos, leading to a shortage of males. One reason is to maintain a sustainable kangaroo products industry. When hunters kill alpha males, female kangaroos are more likely to mate with weaker males, leading to weaker young. If stronger females are killed, males may avoid females that are poor breeders.

I think the problem with culling is that the targets tend to be strong, halthy individuals, rather than weak ones. This could lead to a fall in the population, along with may of the survivors being less able to produce healthy offspring.

I'm afraid I'm not an expert in this subject and I would prefer it if Australia still had large carnivorous marsupials that could control kangaroo populations by weeding out weaker individuals.

I hope this helps

All the best

Jonathan  

Wild Animals

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Jonathan Wright

Expertise

I can answer questions about wild mammals and other animals, as well as extinct animals and zoos. I am not an expert about every animal species. I can look up information from books and the internet, but can't verify if all the information is true. Please don't ask questions about: 1. Pets. I am not a vet. Please contact a vet if your pet is ill. You may need to spend some money if you want your pet to live. Don't get a pet if you don't know how to look after it and if you can't provide it with the space, food and possible companions that will help it live a healthy life. Don't take animals from the wild, unless they are ill and/or injured and you can protect them until a wildlife charity can help. It is cruel to take animals from their parents, especially if the parents will look for the babies, while putting their other babies at risk. You may be breaking the law by keeping wild animals or you may need a licence to look after some species. Please check with a local wildlife group. 2. Eggs: Please don't remove eggs from nests. The mother birds provide the right temperature for the eggs and won't sit on them if the temperature is warm enough for them to develop naturally. It is illegal to remove eggs of some species and, unless you have an incubator or a broody hen, the egg may not develop. If you are allowed to touch the eggs, you can candle them to see if they are fertile. If theys aren't fertile, they won't hatch. 3. Fights: Please don't ask about fights between different animals. These questions assume that individuals of two species fight each time they meet and that one species will always be victorious over another. This is untrue. There are cases where a live mouse has been fed to a venomous snake, bitten the snake leading to the snake's demise. 4: Diseases: Please ask doctors or other medical experts about diseases that you may catch from animals. I can't advise on how to deal with viruses, bacteria etc.

Experience

I have a zoology degree and have been interested in animals since I was two. I am a zoo volunteer at London Zoo. I have appeared on a BBC Radio Quiz, 'Wildbrain'.

Organizations
WWF. ZSL. Natural History Museum. RSPB. London Bat Group.

Publications
Newsletters of London Zoo volunteers and the London Bat Group

Education/Credentials
BSC degree in Zoology. 'A' level in Zoology. 'O' Level in Biology.

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