Sexual Behaviour of Chickens: Improving Fertility and Welfare

Tom Pizzari’s research group studies chickens and the mechanisms that determine their reproductive success.

This research gives us a better understanding of sexual behaviour more generally and helps to improve the management of fertility and genetic diversity in food animals.

Their experimental approach uses the red junglefowl, the wild ancestor of the chicken, as a baseline to understand reproductive patterns under natural conditions and the way these have changed due to domestication.

On the left, a red jungle fowl, Gallus gallus, and on the right,
a domesticated broiler chicken, 
Gallus gallus domesticus.

Tom Pizzari and his team are studying the complex set of interacting traits that determine fertility, from the social interactions between male and female birds to the physiological interactions of gametes. Because sexual interactions play a key role in animal health, for example through aggressive mating behaviours and patterns of sexually-transmitted infections, this work also has potentially significant implications for animal welfare and biosecurity.


Pizzari’s team have found that fowl populations are highly sexually promiscuous and that, as a consequence, variation in reproductive success is determined by the complex behavioural and physiological interactions between males and females. These many subtle effects, when acting in combination, have a large influence on fertility and hatchability.

Female fowl can store sperm from multiple males for three weeks, and can bias the fertilisation success of an insemination after mating through different cryptic mechanisms of sperm selection. Similarly, males can change the amount of semen allocated to individual hens according to a number of factors, including genetic similarity between partners, social status, the fecundity of a female and her sexual novelty. Because of these dynamics, reproductive success can change over time and across flocks. Understanding these patterns of variation can help breeders devise effective strategies to improve the fertility and welfare of a flock by managing its social environment.

Pizzari’s team are currently studying the proteins contained in the seminal fluid of males and their role in fertility and reproduction. They are also looking at the microbes present in the genital tract of these birds, their possible effects on health and fertility, and how these microbial communities change as they are passed from one bird to another.

Wider interest

A better understanding of what determines reproductive success has the potential to improve management of chickens bred for food. The results of this research allow breeders to characterise and predict reproductive behaviour and performance, which can help ameliorate infertility problems faced by the poultry industry. This has the potential to improve both economic benefits and welfare of the flock. To this end, the research group has been actively collaborating with an industry partner, Aviagen Ltd., one of the world's premier broiler breeding companies, to optimise fertility in British broiler breeder flocks.Tom Pizzari’s research group studies chickens and the mechanisms that determine their reproductive success.


This research is funded by NERC and BBSRC.

Read more

Professor Pizzari's profile on the Department of Zoology website

Photos of red jungle fowl (top and in text) and broiler chicken from Wikimedia Commons