Response of pheasants to predator calls: measuring 'wildness' and strain effects.

Abstract

In the United Kingdom there has been a great deal of concern over the potential impacts of rearing on the flight characteristics of common pheasants Phasianus colchicus during driven shooting. A number of theories have been proposed that might explain this phenomena including changes in behaviour of the birds has occurred because of rearing. The suggestion being that the rearing systems used in the United Kingdom are making the birds more 'tame'. In the United Kingdom, numerous 'strains' of pheasants have been released over the last few years which are purported to exhibit 'wilder' behaviour resulting in superior flying. We used a tape-recorded raptor caIl as a 'wildness' model to elicit various anti-predator behaviours from 5 strains of the common pheasant. We selected a standard British game farm strain of pheasant, a recently imported' American' strain purported to be 'jumpy or wild', a strain derived in the early 1990s from wild 'Fen' stock (Fenlands of England) for which smaller size was selected to be used as breeding stock over 4 years, imported Scandinavian pheasants, and Japanese-cross pheasants for behavioural analysis. We reared the birds together, under identical conditions, to control for rearing effects on behaviour. At ages 4, 8, and 12 weeks we randomly selected groups of 5 birds including each of the strains and placed them in an observation pen. We played a tape-recorded buzzard Buteo buteo call for 30 seconds and then monitored behaviour for 3 minutes. We classified behaviours as crouching, alert, fleeing, feeding, resting, and walking. Using compositional analysis we found that behaviour differed from random at age 4 weeks (P < 0.001), 8 weeks (P < 0.001), and 12 weeks (P < 0.001). Strain effect on behaviour was only significant at age 4 weeks (P = 0.002). Individual behaviour appeared to be influenced by the other birds within the 5-bird groups tested together for all three age classes (P < 0.00 I). Using the predator call as a model for measuring 'wildness' in hand-reared pheasants we were not able to distinguish among genetic strains other than in the youngest age class. It appears that anecdotal observations of 'jumpy' pheasants possibly explaining perceptions of better flight might be more related to environmental influences on behaviour and observer expectations rather than true genetic differences among the strains.