In last month’s blog, I talked about traditional selective breeding, what it means, how it is done, and what its impacts have been in terms of the productivity of modern meat chickens and flow-on benefits for consumers. I hinted that in this month’s blog I would discuss whether and how selective breeding might have changed bird behaviour in the course of the development of modern meat chicken breeds, and I invite readers to join me on a journey through the behavioural repertoire of a modern meat chicken.
That journey starts here.
Chicken behaviour is something that’s very close to my heart. Why so? Because it’s essentially what I did my research on here in Australia and overseas – albeit many years ago! And far from being an esoteric subject, chicken behaviour is a serious and important issue, not just for the chicken, but because it’s a critical tool that chicken farmers use in managing the flocks in their care on a daily basis.
But first, let’s get back to the question I posed in last month’s blog….
Has selective breeding affected the behavioural repertoire of a modern meat chicken?
Well, the answer is that modern meat chickens probably have the same repertoire of behaviours as their ancestor, the Red Jungle Fowl (Gallus gallus) of South East Asia, but certainly the extent to which they display these behaviours has changed.
One thing that certainly hasn’t changed is that chickens are social animals; they live in flocks. Heard of a ‘pecking order’? Well the term originated with chickens and, yes, modern chickens also have one, albeit not so obvious in meat chicken flocks because they are young birds, which are not generally kept to their potential adult age. To establish a pecking order chickens do show aggressive behaviours towards each other (how else do they establish a pecking order…by counseling perhaps?), and it’s common to see play or practice ‘sparring’ encounters between pairs of birds in young meat chicken flocks.
Chickens also communicate vocally with their flock mates.
One obvious manifestation of their flocking tendencies is that, even in the large flocks kept in some meat chicken sheds, they tend to congregate in loose ‘groups’ across the shed area, rather than spreading themselves out absolutely evenly across the available floor area. Indeed, one research study (K. Febrer, T.A. Jones, C.A. Donnelly and M. Stamp Dawkins M (2006) Forced to crowd or choosing to cluster? Spatial distribution indicates social attraction in broiler chickens Animal Behaviour 72: 1291-1300) showed that even at stocking densities far exceeding those ever used in Australian commercial chicken farms, meat chickens in commercial houses consistently spaced themselves closer to other birds than would be expected if they were just placing themselves at random, or if they were avoiding each other.
One very fundamental behavioural change is that modern meat chickens are more ‘docile’ or less flighty and less fearful of humans than their ancestor the Red Jungle Fowl. This feature is not unique to modern chickens…it is a characteristic typical of all animals that have been domesticated over the centuries (in the case of chickens, probably over tens of thousands of years). In fact, recent research conducted by a team of behavioural geneticists at Linköping University in Sweden has shown that simply selecting Red Jungle Fowl for reduced fear of humans leads to co-selection for a range of other traits of value to humans. Even after just three generations, the birds selected for ‘tameness’ grew faster, laid larger eggs and produced larger offspring than their more fearful counterparts (B. Agnvall, A. Ali, S. Olby and P. Jensen (2014) Animal Volume 8 Issue 09 September 2014, pp 1498-1505). More recent evaluation of the fifth and sixth generation of the selected birds apparently has shown that the tamer birds also gained more weight per kilogram of food consumed i.e. they were more efficient.
Exploratory and foraging behaviours
Chickens explore their environment – with their eyes, their beaks and their feet! In the wild, they required these behaviours to uncover food and water. In fact, chicken farmers exploit this to ensure that the day old chickens which arrive in their sheds quickly learn to find drinking water from equipment which you and I would probably not intuitively associate with delivering water.
Chickens are omnivores, and their wild and backyard relatives eat seeds and other plant materials, insects, worms and other small animals, and even scavenge on the carcasses of dead animals (even of their own species). They therefore have quite a high requirement for protein. This hasn’t changed in the modern meat chicken, and chicken diets are formulated to meet these requirements.
Because they have been bred and are reared in conditions where they have food in front of them 24 hours a day, meat chickens are, not surprisingly, less active than their wild ancestors. However, they still display a range of foraging behaviours in their shedded environment, which includes pecking at and scratching in the litter (for example, sawdust, wood shavings or rice hulls) on the floor of their shed. Due to their somewhat altered body shape compared to their ancestors – more muscle, particularly breast muscle – the way that they walk looks different….to make an analogy in the world of sports, a bit like comparing how a shot putter walks compared to a marathon runner.
Meat chickens in commercial sheds possess and do display the full gamut of comfort behaviours seen in their wild ancestors – resting, preening, stretching, wing flapping and even dust-bathing!
To stay comfortable, chickens regulate their temperature by moving themselves into more comfortable locations! They don’t have sweat glands, so if they are too hot they will attempt to lose heat by panting to lose heat from their respiratory tract and by holding their wings away from their body to maximise direct heat loss to the environment. If they are too cold they will huddle together to keep warm.
Alert but not alarmed! – predator awareness and avoidance
Although essentially protected by virtue of their relationship with their human keeper and the housing provided from predation by the likes of foxes, cats, birds of prey etc, modern meat chickens have retained their fear of predators and display a range of behaviours to protect themselves from predation. They show very distinctive responses to visual stimuli or sounds that might represent a predator bird overhead, for example, and farmers need to be careful not to expose them to sights or loud noises which might panic them.
Interestingly, meat chickens which have access to an outdoor range tend to display more behaviours associated with fear and alertness for predators than they do when they are inside their shed.
Why is behaviour important?
The issue of how important is it to the chickens themselves for them to perform certain behaviours is the subject of much conjecture and scientific debate, although it is clear that some behaviours are more important (or more motivating) for chickens than others. This is a topic for another day.
However, where it becomes really important in chicken farming is that farmers use key chicken behaviours in a myriad of ways to monitor and manage their flocks… even though sometimes they probably don’t even realise they are doing it – it is just part of the ‘art’ of being a good chicken stockperson. Forget all the manuals, modern technologies, controllers and other assorted gadgets that all farms can and do have to help farmers manage their flocks – the key attribute of a good farmer is their ability to ‘read’ their flocks.
How they do that? Well, join me next time to learn more about how chicken farmers use chicken behaviour to read their birds’ needs.