Some years ago, as part of my studies in biology, I applied as a research assistant to a research station owned by Stockholm university. Note, this was not a paid job, but more like a very practical university course. My task was to assist a senior student with her thesis work, but as I had a lot of time on my hands, I also helped out with some other projects going on at the time.

All the projects that summer were about domestic poultry. Chickens. The project I was supposed to do most work with was about their vision. By teaching them to peck on certain colours for food, we could later test how well they distinguish different hues. If a hen was taught that blue yielded treats, and green did not, and we gave her more and more similar coloured lights, when would she have trouble choosing? Turns out, chickens are much better at this than humans. They picked the correct light even when I did not spot the difference.

Anyway, at the same time two other projects with hens were on-going. One of them was a little research project, in which they wanted to test whether hens could tell apart the smell of a predator and a non-predatory animal. This was done by putting the hens in different rooms. Dung from 2 different non-predatory animals (elephant and deer, if I remember correctly), and 2 different predators (tiger and dhole), which was retrieved from a zoo. And then keep score on how much they did alarm calls vs how much they foraged for food. Turns out chickens are afraid of tiger poop.

And, here comes the project which you might find interesting, dear zoos: How do hens choose their mates? In a natural jungle fowl flock (red jungle fowl are the ancestors of our modern chickens), there are several hens and a couple or so roosters. Roosters are often more interested in mating than the hens are, but sometimes the hens initiate mating by laying down in a mating position in front of the rooster. In this experiment, siblings had been isolated from each other before hatching. Now, evolutionary, it makes sense to avoid mating with one's siblings (inbreeding). But will the birds know who is their actual biological sibling? The experiment was carried out by creating small flocks, with two hens and two roosters. One of the roosters will be the brother of one of the hens. Now, will they prefer to not mate with each other and choose the other potential partner? This was measured by looking at how much the hen consented to the mating! Yes, when helping out with this project, I learnt how to score poultry matings from a scale of 1-5, where 1 was violent rape/escaped kicking and screaming, and 5 was that she initiated it by laying down in front of him. We kept score on how much she consented to the mating, and compared whether there was a difference between mating with her long-lost brother, or the unrelated rooster. Similarly, we kept track on how much the rooster tried to rape mate with his sister versus the unrelated female. This set-up was then repeated again, and again, with different families.

The preliminary results? Roosters either don't recognize siblings, or don't care, because they will try to mate equally with all hens. Hens on the other hand, will be more eager to mate with unrelated roosters, and will try to avoid being mated with their brothers.

**tl;dr: I helped with zoological research, among them a project in which we kept track of chicken sexual consent. It's possible. **