Title:
|
Use of space by laying hens : social and environmental implications for free-range systems
|
The use of space by laying hens in free-range systems is often very uneven, with birds displaying an apparent reluctance to leave (and move away from) the house. Using mainly small groups as models for the larger flocks normally housed in commercial free-range systems, this thesis investigated the role of social and environmental factors on hens' movement and use of space. Hens displayed a greater readiness to emerge from a familiar covered box into an unfamiliar outdoor area when the outdoor area contained familiar feeders, even though the birds had free access to food in their home pens. Emergence latencies decreased with repeated testing. Birds also spent more time in the outdoor area when feeders were present, though they tended not to move past the feeder which was nearest the box. Birds which had been exposed to an enriching stimulus (traffic cones) in their home pens tended to leave the box earlier than those which had not, thought this was not dependent on the actual presence of cones in the outdoor area. This suggests that a more complex home environment can influence birds' responses to novel environments. Furthermore, the order of emergence into the paddock was not significantly influenced by social rank. Birds which had been regularly exposed to the outside environment during the rearing process displayed little or no fear of the outdoor area as adults. In contrast, regular handling had little effect on birds' readiness to enter the outdoor area. Regular exposure to the outside environment also reduced birds' underlying fearfulness (measured by tonic immobility), both in small experimental groups and in a larger free-range flock.
|