Hedgerow management for the conservation of grey Perdix perdix and red-legged Alectoris rufa partridges in the British Isles

In Britain, both native grey partridge Perdix perdix and red-legged partridge Alectoris rufa (native to mainland Europe and introduced as a gamebird) almost exclusively use hedgerows and other field boundaries for nesting. This paper summarises the evidence for the importance of hedgerow vegetation characteristics to partridges and identifies the most suitable methods of hedgerow management for partridge conservation.

Ten farms (nine in southern/eastern England, one in Scotland) were selected for study of within-farm variation in partridge breeding density from 1979 to 1981. During March all fields were surveyed and breeding density calculated. Four farms were searched for nests, and the outcome of each nesting attempt recorded.

Field boundaries/hedges on all farms were surveyed in late winter just prior to partridge nest-site selection, the following was recorded: boundary length, width and height; bank height; amount of dead grass, nettle Urtica, bramble Rubus fruticosus, and ground cover; visibility through ground cover; number of trees and gaps; and presence of wire fence or ditch.

Around each nest and at a randomly chosen 'non-nest' site within 100 m of a nest, similar characteristics were recorded, as well as: amount of leaf litter, ground vegetation height, and distance to nearest tree and gap (rather than number).

Recruitment: Higher grey partridge recruitment was closely correlated with three nesting habitat characteristics: total amount of field boundary, amount of dead grass and height of earth bank at hedge base. Likewise for red-legged partridge, correlation was found with three nest-site characteristics: total field boundary; number of gaps, and amount of nettle in the hedge.

Breeding density: Grey partridges occurred on nine of 10 farms. Breeding density was closely correlated with the length of field boundary on seven. Boundary length and the amount of dead grass in a hedge base were the only two variables significantly and consistently related to breeding density. Similarly, on six of the eight farms with red-legged partridge, breeding density was significantly correlated with boundary length, nettle cover also appeared important.

Nest-site selection and nest predation: Of the 42 grey partridge nests found (24 hatched, 14 predated, four deserted), these were sited where dead grass, bramble and leaf litter were significantly more abundant than in surrounding boundary vegetation and bank height was higher. Of 65 red-legged partridge nests, location was likewise influenced. The only habitat difference between successful and predated (red-leg) nests was height of surrounding ground vegetation.

Boundary management: Seven management regimes (1,266 boundaries sampled) were evident: 1) unmanaged (37.2%); 2) occasionally managed (6.6%); 3) boundaries with verges cut (5.3%); 4) cut annually (24.6%); 5) cut biennially (12.4%); 6) annually cut sides (7.5%); 7) regularly grazed (6.3%). The most suitable nesting habitat was in hedges trimmed biennially.

Conclusion: Where both the total amount of field boundary and ground vegetation was high, so were partridge populations.

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