Masturbation in birds

Outline of the project:

One of the projects I work on is trying to understand why some species of bird seem to masturbate loads, and other species don’t seem to do it at all. Masturbation is a pretty interesting behaviour, seen in loads of animals, from tortoises to horses, squirrels, and dolphins, as well as in humans, chimps and bonobos. But despite being so widespread, no one really knows why it happens in most of these species. There are lots of theories- it might be simply for enjoyment (in evolutionary terms, possibly a byproduct of animals having evolved to enjoy sex). Alternatively, it could be a maladaptive behaviour mainly seen in damaged animals (which might explain why it is often seen in captive animals). Or it could be a way of reducing stress. Others have suggested that it is a way for male animals to get rid of old, poor quality sperm, enabling them to use their best sperm the next time they have sex. Another theory is that it helps prevent infections by flushing out the reproductive tract. Or it could be a pair bonding behaviour. There are lots of other ideas as well, and at the moment, there has been little systematic examination of this behaviour (although Ruth Thomsen at UCL has done some good work on the topic). As an evolutionary and behavioural biologist, I’d like to understand what’s going on.

SONY DSCSONY DSCAvocets (Recurvirostra americana) in Morro Bay, CA

A few of the bird species reported to masturbate in the wild- spectacled parrotlets, a northern lapwing, and an American Avocet


Masturbation has been seen in some birds. This is interesting because most birds have sex using their cloacas- these are single orifices that are used to defecate, urinate, and transfer sperm (in males) and accept sperm and lay eggs (in females). Cloacas don’t seem to have the nerve clusters seen in mammalian penises and clitorises, so most people think birds don’t have an equivalent of the mammalian orgasm when they have sex. If this is true, then several of the theories about why animals masturbate may not apply to birds. Birds also have a massive range of social systems, and ecologies, and there is an enormous amount known about the biology and behaviour of many birds species, thanks to the huge numbers of people interested in birds (naturalists, birdwatchers, falconers, bird-keepers, and scientists). Also, birds are typically active during the day, so there is a real chance that people will have seen them masturbate if they do regularly do it. More importantly, people might also know some species well enough to convincingly argue that it doesn’t masturbate. This kind of negative information (e.g. species that definitely don’t masturbate) is really hard to find in these kinds of behavioural studies. For example, definitely saying that a mammal species doesn’t masturbate is going to be really difficult for most mammals (because so many are nocturnal, and avoid people). So we are hopeful that there is enough information on birds to realistically work out which species do and don’t masturbate, and whether this correlates with any particular life style, breeding system, or clade.


How this project came about:

Chloe Heys, a PhD student here at Liverpool, has a parakeet called Billy. Billy masturbates loads. Dozens of times a day at the right time of year. She was a bit worried about this behaviour- was he doing it because he likes it, or was it because before she rescued him he was not in a great situation? So she mentioned it to me, and we looked into it, and were shocked by how little biologists know about why animals masturbate. So we thought we’d start up a project and try to find out. We then went to Kevin Arbuckle, another PhD student at Liverpool, who is expert on the analysis of data about how traits change between species, and the project has been growing since then.

Chloe and Billy P1070229kevin

The team: Chloe Heys (and Billy the parakeet), Tom Price, and Kevin Arbuckle


Reporting masturbating birds:

We are interested in getting more data about which bird species masturbate. However, we are a bit worried about simply asking every birdwatcher and birdkeeper to tell us if their bird masturbates. Although this would get us lots of great data, we think at least some of the responses we would get would be from jokers, and we wouldn’t be able to tell the good data from the bad. So, to keep the quality of the data high, at the moment we are only asking for data from professionals who work with birds- zookeepers, aviary keepers, falconers, scientists, and others. If you are a professional working with birds who would like to report masturbation in a species, or if you think you know a species well enough to be convinced it does not masturbate, then we would really appreciate it if you would send me an email and I’ll forward you a short questionnaire (it will only take a couple of minutes to fill it in). We would really appreciate it!

Emails to:



Well, we’ve some really nice articles based on this out in the Audubon Magazine (the premier magazine for birders in the USA), and also at Cosmopolitan:


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