Individual study: The relationship between ring-necked pheasant Phasianus colchicus release pen proximity and grey partridge Perdix perdix population parameters at the Sussex Downs Study Area, Sussex, England
Ewald J. A. & Touyéras H. (2002) Examining the spatial relationship between pheasant (Phasianus colchicus) release pens and grey partridge (Perdix perdix) population parameters. Zeitschrift für Jagdwissenschaft, 48, 354-363
In the UK, grey partridge Perdix perdix numbers have declined over recent decades e.g. due to agricultural intensification. In response, shooting estates have moved from management for wild grey partridges to rearing and releasing non-native ring-necked pheasants Phasianus colchicus. This has led to concern about adverse effects on grey partridges, including competition between the two species, and the possibility that parasites (especially the caecal nematode, Heterakis gallinarum) carried by pheasants may be partially responsible for grey partridge declines. Long-term monitoring data from two sites in lowland southern England were analysed to look for relationships between proximity to pheasant release pens and grey partridge population parameters. Summarised here are the results from one of these sites in the Sussex Downs.
The dataset analysed was from the 62 km² Sussex Downs Study Area of The Game Conservancy Trust (0º24'25, 50º53'17) in Sussex, southern England. Records of autumn counts of grey partridges were available for 33 years (1968-2000). Numbers of released pheasants were not known.
The location and use of pheasant release pens varied over time; these were mapped onto a GIS (geographical information system). Statistical tests for differences in grey partridge population parameters before and after pen use thus needed to take individual pen location and use into account: concentric bands of 0-100 and 100-200 m from each pen and woodland were created within the GIS map; each area within 200 m of pen location in each year (whether or not a pen was present) was considered as a replicate block of data in the analysis.
In the study area, density of pheasants before the autumn release of young pheasants from pens and the density of spring pairs of grey partridges both declined. The density of release pens increased over time; data from shoots within the study area indicated that the number of pheasants released increased in line with the increasing number of release pens
However, no effect of proximity to release pens on grey partridge density, fecundity or survival was found, even as the density of pens increased.
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