The effects of improvement of upland, marginal grasslands on the breeding success of Lapwings Vanellus vanellus and other waders.

Abstract

Data on the breeding success of Lapwings Vanellus vanellus on unimproved and improved grassland, with comparative data for arable land, were obtained from a study on 760 Lapwing clutches. The study was undertaken in the Eden Valley, Cumbria, and Teesdale, Co. Durham, between 1985 and 1987. First clutches were larger on unimproved grassland with a mean of 3.73 eggs compared to 3.61 eggs on improved grassland. In contrast, replacement clutches were larger on improved areas (3.90 eggs) than on unimproved (3.47 eggs). On average, 40% of eggs laid on unimproved pastures hatched compared to only 17% on improved pastures. No significant difference in hatching success was found between unimproved and improved meadows with 32% and 22% of eggs hatching, respectively. Overall, 73% of unsuccessful first clutches were replaced on unimproved pastures, whereas on meadows and improved pastures combined, only 32% were replaced. Survival of small chicks was highest on unimproved areas. Production on unimproved areas was sufficient to replace adult losses and so maintain numbers, whereas on improved land production was too low to maintain existing breeding densities. Hatching success on unimproved areas was similar for the four species of wader considered. On improved areas, Redshank hatching success was relatively high, with 54% of pairs producing chicks, compared to 35% for Lapwing and 23% for Curlew.