Wildlife fertility control research
Can we improve the welfare of some species of wild animals by treating them with contraceptives?

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This profile is tailored towards students studying biological sciences and psychology, however we expect there to be valuable open research questions that could be pursued by students in other disciplines.

Why is this a pressing problem?

There are an enormous number of wild animals in the world, vastly outnumbering humans and domesticated and farmed animals. Yet the welfare of wild animals is a highly neglected area of research when contrasted with research on the welfare of humans or domesticated animals. Some plausible hypotheses regarding the distribution of welfare among individuals of different species of wild animals have nonetheless been put forth. One is the argument from life history, which describes how fecundity and life-span might be related to welfare. This argument states that highly fecund animals will produce offspring in excess and most individuals will perish before reaching sexual maturity, sometimes due to a lack of available resources. Such exceedingly short life-spans will probably have lower average welfare than the lives of the few lucky individuals who survive until adulthood, although adult animals may also suffer from a lack of food, water, or shelter due to resource constraints.

If a lack of resources is indeed a common issue for wild animals, and if the argument from life history is broadly correct, we would expect fertility control to have positive effects on the average welfare of the target species through increased condition and survival of the remaining individuals, as long as possible side-effects of the treatment can be avoided. A lower population size would plausibly lead to reduced competition for resources, which ought to lead to higher average welfare, and possibly also higher total welfare. This is a bit more than just a theoretical argument though; humans have already escaped the Malthusian trap we were in, partly by artificially reducing our own fertility.

Although wildlife contraception research has been conducted for decades – for example, oral contraceptives have been used on pigeon and squirrel populations, and contraceptive darts to control deer populations – it has generally not focused on the welfare impacts of contraception. More research in this direction could help us find promising opportunities to improve wild animal welfare. Improving wild animal welfare is often seen as an intractable problem, so finding and thoroughly investigating promising small scale and near term solutions like contraception also seems like a very promising way to escape a vicious cycle of helplessness and disinterest.

See the video below on how wildlife fertility control can improve animal welfare.

Explore existing research

The Botstiber Institute maintains this archive of research related to wildlife fertility control.

Organisations doing related work include:

Find a thesis topic

If you’re interested in working on this research direction, below are some ideas on what would be valuable to explore further. If you want help refining your research ideas, apply for our coaching!

Both empirical and theoretical studies are needed to determine the most promising conditions in which contraceptives could improve wild animal welfare.

Important areas for exploration include: the circumstances in which decreasing the population of one species leads to population growth in another, potentially eliminating positive effects; how different delivery methods for contraceptives affect individual welfare and what the side effects of these methods are; and how the welfare effects of reduced population differ between solitary and social species (for example, more social species may be negatively impacted by having fewer individuals to cooperate with).

Here are some more specific ideas, suggested by the Wild Animal Initiative in this post, that a thesis or dissertation question could be based on: 

  • Empirically or theoretically test whether and how sociality [the degree to which animals in a population tend to form social groups] interacts with the potential welfare effects of contraception. 
  • Empirically test the welfare effects of a contraceptive agent, with a focus on both the direct and indirect effects on individuals within the population. See an example for such a project on pigeons. Another target could be rodents (using, for example, the product ContraPest) or other species that have high fertility (with potential to improve the welfare of many individuals).
  • Empirically test whether different delivery methods have different average welfare outcomes, and whether it is possible to predict which method will suit different types of species.

Work on abundant species that produce a lot of offspring, such as rats, pigeons and prairie dogs, seems particularly promising, as there is the potential to positively impact a large number of individuals.

This post from the Wild Animal Initiative suggests empirically exploring ‘the factors that determine perceptions of wildlife contraceptives, and determine public support for making improvements beyond the ‘natural’ welfare-level as opposed to just minimising harms.’

If you’re interested in exploring the moral importance people assign to non-human animals and how to increase concern for their well-being, you might also be interested in our profile on moral circle expansion.

Further resources

You can watch the presentations from the 2022 International Conference on Wildlife Fertility Control held by the Botsiber Institute here.

See this list of research priorities from the Wild Animal Initiative for further research ideas.

If you’re interested in working on this research direction, apply for our coaching and we can connect you with researchers already working in this space, who can help you refine your research ideas.

If you want to do research on wildlife fertility control, we also recommend applying to join the Wild Animal Initiative’s online research community. You can also apply to join our community if you’re interested in peer connections with others working in this area.

Apply for our database of potential supervisors if you’re looking for formal supervision and take a look at our advice on finding a great supervisor for further ideas.

Our funding database can help you find potential sources of funding if you’re a PhD student interested in this research direction.

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Sign up for the Wild Animal Initiative newsletter and Animal Ethics newsletter to stay up-to-date with news in this area.


This profile was last significantly updated in April 2022 based on this report from the Wild Animal Initiative. The thanks for first writing this profile to Simon Eckerström Liedholm. Learn more about how we create our profiles.

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