The efficacy of a technique to control parasitic worm burden in pheasants (Phasianus colchicus) in the wild.

Abstract

Research on the breeding success of pheasants (Phasianus colchicus) in the wild has shown that juvenile reared birds (those entering their first breeding season having been reared and released the previous summer) have lower breeding success compared to their wild counterparts (Hill and Robertson, 1988: Brittas et aI., 1992: Leif, 1994: Woodburn, 1999). In recent years the Game Conservancy Trust has been researching ways of trying to improve the breeding success of reared pheasants in the wild. In one study the effects of the caecal nematodes Heterakis gallinarum and Capillaria spp., both of which are common parasites in pheasants, were investigated (Woodburn, 1999). Only juvenile hen pheasants were used in the study, some wild and some reared, and all were radio-tracked throughout the breeding season. Half of the reared hens were orally dosed with an anthelminthic in spring and the other half and the wild group were given equivalent amounts of water. The results showed that chick production of dosed reared hens was twice that of undosed reared hens, but there was no difference between dosed reared hens and wild undosed hens. The main result was the improved survival of dosed hens during incubation. Earlier research on red grouse (Lagopus lagopus scoticus) showed that heavily parasitised hens had altered scent emission, making them more vulnerable to scent-hunting predators, such as the red fox (Vulpes vulpes) (Hudson, 1992). It is likely the situation may be similar in pheasants.
In a separate study it was found that the provision of supplementary food throughout the spring enabled hens to achieve improved body condition at the onset of the breeding season, a time when they need to build up their body reserves in preparation for egg-laying and incubation. Many gamekeepers stop feeding pheasants around February, and together with modem farming methods, this often results in there being very little natural high energy food available to them. As a result of supplementary feeding hens were in better condition and showed improved productivity (Draycott et al., 1998).
This paper describes a pilot study in which the above two factors, supplementary feeding and dosing, were combined. It aimed to test if providing anthelminthic treated grain in spring was a feasible means of adequately dosing wild (free-living) pheasants. An experiment using captive hen pheasants was therefore carried out to try to assess the best time to dose pheasants in the wild to maximise the benefits of the treatment.