Comparative breeding success of wild and reared pheasants (Phasianus colchicus) in southern England.

Abstract

A pheasant population, Phasianus colchicus, comprised of wild and reared birds, was monitored intensively between 1988-1994 on a 400-ha area of mixed farmland in north-eastern Dorset, England. A sample of 142 females was fitted with radio-transmitters, while the remaining 127 females and 327 males were fitted with individually recognisable poncho-type neck tags before being released. The aim of this study was to measure the effects of origin, wild or reared, and age, juvenile (i.e. in their first breeding season) or adult (i.e. in their second or following breeding season), on territoriality, harem size and breeding success. There was no difference in the likelihood of adult reared males and wild males becoming territorial, but both groups were more successful in establishing a territory (80%, n = 54, and 93%, n = 27) compared to juvenile reared males (45%, n = 144). However, adult reared males attracted a greater number of females (3.4 per male, n = 25) to their harems than both wild (1.5 per male, n = 44) and juvenile reared (1.6 per male, n = 70) males. Adult reared females attempted to nest more often [1 .11 ± 0.25 (SE) attempts per female, n = 9] than both juvenile reared [0.53 ± 0.1 (SE), n = 64] and wild females [0.57 ± 0.11 (SE), n = 49]. Wild and adult reared females successfully hatched more chicks (1.5-1.9 per female) than juvenile reared females (0.7 per female), despite little variation in clutch size (8.3-10.1 eggs) between groups. Overall, reared pheasants exhibited poorer breeding success than wild pheasants in their first year, but if they survived until their second year then they exhibited similar reproductive performance to wild pheasants. Several factors, such as early display and dominance for males, body condition prior to incubation and choice of suitable nesting site for females, may contribute to the improved performance of reared pheasants with age.