The Fate and Management of Pheasants (Phasianus colchicus) Released in the UK.

Abstract

The system of releasing hand-reared pheasants into large open-topped pens, employed in many parts of the UK is a successful method of delivering mature pheasants (with some level of adaptation to the wild) for shooting on professionally managed estates. The movements and mortality of 486 hand-reared pheasants released into six independent open-topped pens over a three-year period were studied with the aid of radio-telemetry. The study aimed to accurately document the fate and dispersal of pheasants released onto commercial shoots employing full-time game managers in England, and test the effect of stocking densities (which were experimentally manipulated across years) and other management practices on these things. A better understanding of the movements and mortality of hand-reared birds (between the time of release and the start of the shooting season) and the effects of common management practices may allow game managers to control releases more effectively, to reduce unwanted impacts or to improve the efficiency of a release. Whilst pheasant releasing can provide the economic incentive for game management that benefits habitats and other wildlife, the negative impacts of releasing can outweigh such gains in a variety of circumstances. The Game Conservancy Trust identifies a number of key factors or processes underpinning this potential, which require further understanding (Sage, 2003). Aspects of these are explored within this study. In particular, documenting the movements of pheasants from release sites in a variety of circumstances improves our understanding of the potential for released birds to encounter sensitive habitats and/or wildlife and hence the opportunity to cause damage.
I found that the delay between releasing and shooting, necessary to deliver such birds, results in depleted numbers of the released birds available to shoot. Steady losses occur throughout this period and the extent of mortality varies greatly between release pens. The greatest source of non-shooting mortality was mammalian predation, primarily by foxes (Vulpes vulpes). The average on-estate shooting return from release pens in this study was 30% (36% considering both on-estate and off-estate returns) and this compares favourably with other releasing systems employed in Europe and the USA. There was no relationship between survival of the radio-tagged birds and stocking density; increasing the number of birds released did not increase the number of birds that were shot. The proportion of the released cohort that were shot was significantly reduced as the stocking density of the pen was increased, however. This suggests that less birds could be released to achieved desired bags if all release pens were stocked at lower density, but this gain would most likely involve an increase in the number of release pens in use, if bags are to be maintained. Survival to the start of the shooting season increased with delayed release dates. This suggests that an optimum releasing strategy, in terms of survival, would involve delaying the release of birds until late August or early September, and leaving a minimum appropriate time interval for birds to mature before commencing shooting. This presents logistical problems however, as limited stocks are available in late August or early September due to the constraints of the natural breeding season.
Departure from the release pen occurred 30 days after release on average and was affected by the opening of pen gates, which was in turn influenced by the level of stocking in some pens. Less than half of the tagged pheasants departed permanently from the release area and hens were almost twice as likely to disperse away as cocks. The frequency of permanent dispersal away from the release area was negatively correlated with the date of release. Hens moved further from the release pen and had greater home ranges but stocking density did not affect their movements. Most aspects of movement were not influenced by stocking density but the sizes of home ranges for released cocks were affected at some sites. The magnitude and frequency of movement from the release pen do not present a problem to shoots covering large areas, with the ability to site pens away from boundaries but may be problematic when this is unavoidable. Areas where supplementary feeding occurred were used significantly more than areas without feeding.
In a separate side study, the impact of radio-tagging on 10-week old captive pheasant poults was assessed and short-term behavioural changes were observed. Elevated 'comfort' behaviours at the expense of 'survival' behaviours did not persist 24 hours after tagging.