Effects of land use on breeding pheasant density.

Abstract

1. Pheasant breeding density was surveyed in each of 150 square kilometre samples on 43 sites selected from areas with an interest in pheasant shooting or Forestry Commission lands during March, April 1988 or 1989. It was also monitored annually at two sites during 1983-92 and 1989-91, respectively.
2. At any one site, three successive counts at dawn or dusk gave a reliable estimate of territorial male density and an index of female and non-territorial male density. Long-term monitoring at one site (1983-92) suggested that territorial male density was limited by habitat quality.
3. Stepwise multiple linear regressions of pheasant breeding density against measures of land-use within the 150 sample squares found significant within- and between-site effects. Within sites, breeding density was related to the availability of woodland edges with high levels of shrubby cover 30-200 cm in height and arable land. Between sites it was related to the intensity of rearing and shooting, supplementary feeding, grassland and the area of woodland. These variables combined to explain 64 %, 50% and 43 % of the variation between kilometre squares in the density of territorial male, female and non-territorial male pheasants, respectively.
4. The relationship based on the stepwise linear regression gave reliable estimates of breeding pheasant density for 14 independent samples from seven sites. However, it had lower predictive power on a further site which included large areas of set-aside, a habitat type rarely encountered in the original 150 squares.
5. Based on 43 sections of woodland edge on one site surveyed over 3 years, arable crops increased territorial male density , both sexes selected edges rich in shrubby cover 100-200 cm in height, females preferred east-facing edges with seed-bearing trees. These explained 34% and 28% of territorial male and female number, respectively. No relationship between habitat features and breeding sex ratio was found.
6. By quantifying the effects of land use on breeding pheasant density it should be possible to assess the implications of future changes in land use on this economically important bird. Furthermore, these analyses suggest priorities for those wishing to increase breeding pheasant density through new woodland planting and management.