ASSESSMENT OF PRELAYING MOTIVATION IN THE DOMESTIC HEN USING SOCIAL-INTERACTION

While much is known about the hormonal basis of pre-laying behaviour o f domestic hens, Gallus gallus domesticus, little is known about how t he behaviour is initiated or how changes in this behaviour occur. An e xperiment was conducted in which hens had to overcome an aversive task , during the course of pre-laying behaviour, in order to reach a nest site. Twelve hens were tested in four treatments presented as a Latin square design. The test arena was arranged such that hens could approa ch the nestbox only along one corridor, and return to the home pen by another. The four treatments consisted of leaving the corridor leading to the nestbox empty, or placing a hen that was dominant, subordinate or unfamiliar to the test-bird in it. Hens took longer to enter the c orridor leading to the nestbox when there was a dominant or unfamiliar stimulus-bird than with a subordinate or an empty corridor. They also made more attempts to find alternative routes to the nestbox during t he searching phase of pre-laying behaviour when there was a dominant o r unfamiliar stimulus-bird, than with a subordinate stimulus-bird or e mpty pen and made fewer entries into the corridor with an unfamiliar s timulus-bird, but not a dominant or subordinate stimulus-bird or an em pty pen. We suggest that hens are weakly motivated to reach the nest s ite during the searching phase. However, the motivation to gain access to a nest site increases near the start of the sitting phase of pre-l aying behaviour. (C) 1997 The Association for the Study of Animal Beha viour.