Behaviour of Laying Hens Negotiating Perches at Different Heights
Research into the responses of hens on perches is important in order to assess the welfare impact of alternative systems for egg production which incorporate perches in their design. Previous studies suggest that many flight and landing accidents occur in such systems as birds attempt
to move between perches and facilities, resulting in a high incidence of bone breakage. In this study three horizontal perches were set with a gradient between them of 0, 30, 45 or 60 degrees according to treatment. Four groups of 15 ISABrown laying hens were individually exposed to each treatment,
being placed on the uppermost perch (Perch1) with a food reward available at the lowest perch (Perch3). Behaviours performed before reaching Perch 3 were recorded over time. More birds failed to move to Perch 3 in 10 minutes when perches were separated by 45 or 60 degrees. In birds which stayed
on the perches for the full 10 minutes, without reaching Perch 3, downward head movements, calling, intended jump behaviours, side-stepping and wing-flapping decreased significantly with time spent on the perches. Motivation to complete the task, in order to gain the food reward, was high
in all treatments. However, when birds found perches difficult to negotiate, behaviours indicating intention to move to the food decreased with time and the incidence of behaviours indicating frustration and thwarting increased. In non-cage systems such frustration could reduce bird welfare.