An interest sparked more than a decade ago by the favourite pastime of a student’s pet cockatiel has led to a groundbreaking study of masturbation in birds which will improve understanding of crucial and under-examined aspects of bird behaviour and welfare.
Now, after studying the behaviour of 120 species across 22 major groups of birds, a team of evolutionary biologists believe they have found some clues about why birds indulge in self-pleasure.
Their paper has just been published in journal Ecology and Evolution and among its key findings are that juveniles and adult birds are equally likely to masturbate, and that it is more common in birds which have more promiscuous mating systems.
Co-author Dr Kevin Arbuckle, from Swansea University’s Department of Biosciences, said: “Although it may seem a frivolous area of research, masturbation is biologically interesting as it forms a Darwinian puzzle – a trait that appears at face value to reduce the fitness of the creature which possesses it.
“Why did masturbation evolve when it comes at a cost of energy, resources and time that could be better spent finding a mate? It is an area that has received little attention in scientific research. Our study is the first of its kind concentrating on birds and suggests answers to this question.”
The researchers say their results show that masturbation may be a non-adaptive byproduct of high sex drive in species with access to lots of mates, or there may be adaptive reasons such as increasing sexual arousal in females to enable quicker copulation during sneak matings with males other than their social partner.
The data for the paper has been collated over the past decade ever since the favourite habit of Billy, a rescue cockatiel owned by paper co-author Dr Chloe Heys, caught the imagination of the scientists back when they were post-graduate students.
The study is significant because it brings new understanding to crucial aspects of bird behaviour, particularly related to welfare and reproduction. The team hopes it will be of interest to fellow researchers, birdwatchers, pet owners, and bird professionals.
Masturbation in captive birds - especially parrots or cockatiels like Billy - has long been treated as abnormal or problem behaviour caused by stressful social or other conditions in captivity. As a result, the habit has been discouraged, punished, or even subjected to veterinary interventions including drug or surgical treatments.
But the study revealed captive birds were less likely to masturbate than wild birds, and that it was more common in parent-reared rather than hand-reared captive birds, strongly suggesting it is a natural behaviour for many species.
Dr Arbuckle said: “This means in addition to gaining better biological understanding of an unusual trait, our results suggest improvements to the welfare of captive birds by reshaping how we view masturbation behaviours.”
As the practice is often observed in female birds, the researchers say this casts new light on females’ sexual desires and reproductive cycles which may ultimately prove valuable for breeding programmes, particularly of endangered or rare species. They hope their work will help spur further investigations into the sexual behaviours of female animals, an area that is often deeply understudied.
The researchers added: “Non-reproductive sexual behaviours in animals can widely vary in complexity and function. The ability to determine whether they serve an adaptive function and how they persist across evolutionary time, is vital to enhance our understanding.”
The study was a collaboration between Dr Arbuckle, Dr Heys, from the University of Lancashire, Dr Matilda Brindle, from the University of Oxford, and Dr Tom Price, from the University of Liverpool.
Find out more about our other Biosciences research