Effects of supplementary feeding on the body condition and breeding success of released pheasants
|Author:||Draycott, Roger A. H.1|
1University of Oulu, Faculty of Science, Department of Biology
|Online Access:||PDF Full Text (PDF, 0.8 MB)|
|Persistent link:|| http://urn.fi/urn:isbn:9514268687
|Publish Date:|| 2002-11-11
|Thesis type:||Doctoral Dissertation
|Defence Note:||Academic Dissertation to be presented with the assent of the Faculty of Science, University of Oulu, for public discussion in Kuusamonsali (Auditorium YB210), Linnanmaa, on November 11th, 2002, at 12 noon.
Professor Harto Lindén
Doctor William Palmer
The breeding success of released pheasants (Phasianus colchicus) is poor compared with wild ones in Great Britain. Many factors have been cited as possible causes of poor breeding success, including reduced hen condition in the nesting season. The aims of this study were to determine whether reduced body condition due to an inadequate diet contributes to poor breeding success of released pheasants and to demonstrate experimentally the impact of supplementary feeding on their body condition and breeding success. A series of 6 studies of food availability, diet, body condition and breeding success of pheasants was conducted in Britain between 1994 and 2000 to study these questions.
Spring diet and food availability were assessed in a multi-site study. Grains and seeds are important dietary components, but their availability to pheasants and their occurrence in the diet was low on all sites during spring. Grains were only a significant component in the diet on sites where supplementary feeding continued into spring. A spring survey of hen pheasant body condition on 21 sites revealed that fat reserves were higher on sites with spring supplementary feeding compared with sites which ceased feeding at the end of the shooting season (1st February). Further, it was demonstrated experimentally that continuing feeding into spring enabled hens to maintain fat reserves at their winter levels, whereas fat reserves of hens in unsupplemented areas were reduced by up to 50%. Supplementary feeding did not improve survival of hens through the spring, but the pre-breeding density of territorial cocks and hens was increased. Feeding did not significantly influence measured productivity parameters except for aspects of re-nesting ability which were improved by feeding. Overall, the densities of young birds observed during autumn counts were twice as high in plots which had been provided with supplementary grain in the previous spring than in unfed plots.
Although population densities of pheasants were positively influenced by supplementary feeding, breeding success was still lower than that of wild birds. Clearly, there are behavioural and physiological deficiencies which pre-dispose released pheasants to poor performance in the wild. Habitat deficiencies other than adult food availability are likely to be important too; in particular, the quality of brood rearing habitat which influences chick survival. However, the results of this study contribute to our knowledge of the ecology and management of released pheasants and it is recommended that spring feeding should be conducted routinely by game managers to enable released hens to maintain body condition and maximise their breeding potential.
Acta Universitatis Ouluensis. A, Scientiae rerum naturalium
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