Grey partridge supplementations in Oxfordshire and east Gloucestershire, UK

Summary

The grey partridge (Perdix perdix), a UK farmland species that declined 88% between 1967 and 2006 mainly from agricultural intensification, was the subject of a supplementation trial by the Game and Wildlife Conservation Trust and University of Oxford across four sympathetically managed arable farms in Oxfordshire and east Gloucestershire, testing both spring pair releases and autumn covey (family group) releases, methods long known to produce inferior survival compared to wild birds. Chicks from a game farm after at least seven captive generations were hand-reared, then in October-November 2006 and 2007, 20 autumn coveys (five per site) were soft-released after a four-day acclimatization period near tall cover, while in April 2007, 70 pairs were hard-released directly along field edges at two sites; four to five birds per covey and all spring females were radio-tagged. Radio-tracking confirmed released birds generally settled onto release sites and favored crops, field margins and game covers as expected, but predation-driven mortality was severe, reaching 80% within eight weeks for spring pairs and 40-50% for autumn coveys; disintegrating coveys, sometimes disbanding unusually early, led most surviving radio-tagged birds to disperse widely, making further monitoring difficult. Breeding was confirmed in only one spring-released pair and two pairs formed from previously released autumn birds, too small a sample for reliable conclusions. Major difficulties included unsustainably high predation on spring pairs and loss of monitoring ability once coveys dispersed. The project rates itself Partially Successful, concluding autumn covey releases are more viable than spring pair releases but neither reliably established breeding populations.