Re-stocking grey partridge

Key findings

• Releasing flocks of game-farm partridge poults does not result in successful reintroduction because of high over-winter losses. 
•  Fostering bantam-reared or artificially-reared poults to wild barren pairs is more likely to succeed. 
•  Where no barren pairs exist, a nucleus of free-living adults must be established.

As lead partner for the UK Grey Partridge Biodiversity Action Plan (BAP), we have a responsibility to do all we can to achieve the BAP targets, which are to stabilise grey partridge numbers by 2005 and to ensure that the breeding population is above 150,000 pairs by 2010. Given the extent of the partridge decline, this is not an easy task because the species has disappeared from large parts of its former range, and is at a very low density in others. Many landowners and keepers are keen to get partridges back onto their land, but are failing despite appropriate management because too few wild partridges remain in their area.

Re-establishment through releasing is the obvious solution, especially as grey partridges are relatively easy to rear in captivity. However, experience has shown many times over that releasing flocks of game-farm poults in late summer does not work because of high over-winter losses. We have therefore launched a new research project which aims to identify optimal release methods, then produce scientifically sound recommendations for re-establishment using releasing.

The project started with a review of existing and historical rearing and releasing techniques by searching through old gamekeeping and game management books and magazines, and by speaking to a wide range of gamekeepers and other interested parties. The review identified that the ideal system for producing birds for reintroduction would be to obtain eggs laid in the wild, hatch them under captive grey partridges, allow the captive pair to rear the chicks to eight weeks, then either release the chicks with the adults or foster the young to a barren pair of wild grey partridges. However, the review also established that it was most unlikely that wild eggs would be widely available for this purpose.

There was also conflicting evidence about the suitability of captive grey partridges as parents, and about their ability to hatch and raise sufficient numbers of chicks for a releasing programme. Therefore, we needed a compromise that would result in a system that was easy, practical, cost-effective and would produce young grey partridges of sufficient quality for reintroduction.

The most suitable compromise, already used successfully by several keepers, is to obtain eggs from a reliable source (eg. a reputable game farm), hatch the eggs under bantams and allow them to rear the chicks to eight weeks. The young are then fostered to wild barren pairs of grey partridges. An alternative is to hatch and raise chicks under artificial heat sources and foster these to barren pairs. Fostering to barren pairs allows the young partridges to learn behaviour traits such as where to find food and avoid predation and it also holds them to the release site by establishing a parental-bond.

These two systems of chick rearing and fostering are dependent on the presence of barren pairs in the wild. If no grey partridges are present in an area suitable for a reintroduction attempt, it is necessary first to establish a nucleus of free-living adults. The review identified two possible methods for doing this: releasing a captive-reared family covey of full-grown birds in late autumn, and releasing captive-reared pairs in spring.

We are field-testing these chick and adult releasing techniques over the next two years in East Anglia and in Wiltshire/Hampshire. In each of the two study regions, we have chosen one site for an intensive study involving all four release methods. We shall follow the fate of the released birds through the use of radio-telemetry. In each region, we have selected a further 12 extensive sites where only one release method will be used per site. At each extensive site, we shall mark all released young with coloured leg-rings, and monitor the outcome through standardised spring and autumn counts.

The rearing field at Fordingbridge has successfully adopted the techniques required to rear partridges under bantams and has already reared a total of over 4,000 grey partridges. The birds produced on the rearing field include around 40 broods of bantam-reared partridges and 40 broods of partridges reared in a standard game-farm fashion. We also produced 40 family coveys of grey partridges by fostering 15 four-week-old chicks to pairs of ex-laying game-farm birds, for release in late autumn.

We released the first broods after harvest 2004. The released broods appeared to adapt quickly to their surroundings in the wild and behaved much as one would expect a wild covey to behave. Survival, which was 85% in both regions after the first few months after release, was high and dispersal away from the release site was low.  The young appeared to behave much the same as wild broods; they have not moved very far, have not packed together and although these are very early results they are very encouraging.

The next stage of the project involved establishing free-living adult grey partridges at sites where partridge numbers are very low or where the species is absent. We began by releasing family coveys in October 2004 and shall release pairs in early spring 2005. We will assess the survival of the birds by counting pairs in March/April 2005.