Decline of Northern Lapwing Vanellus vanellus breeding on arable farmland in relation to loss of spring tillage

Abstract

Capsule A decrease in the area of spring tillage was not the primary cause of a decline to extinction of a local breeding population of Lapwing. Aims This study tested whether or not the availability of spring tillage limited the number of Lapwing settling on arable land and resulted in a population decline, the ‘spring tillage’ hypothesis. Two predictions from the hypothesis were tested: (i) that between-year differences in the numbers of Lapwing settling on tilled land tracked between-year differences in the area of spring tillage; (ii) that the saturation density was reached on tilled land in each year when birds were present. Methods Breeding birds, nests and fledged young were counted annually on arable land and adjacent grassland and non-agricultural habitats on part of the North Downs, Hampshire, between 1981 and 1995, except in 1987 and 1988. Data on crop development and field attributes were collected concurrently. Results The number of breeding pairs decreased to zero between 1981 and 1995. Over the same period, the area of spring tillage decreased by 40%. Tillage availability partially determined the distribution of fields used for nesting, but there was no evidence that it limited the number of Lapwing settling on tilled land, except in 1984 and, possibly, 1982. Neither prediction of the ‘spring tillage’ hypothesis was upheld. Annual production of fledged young was not sufficient to replace annual losses. Conclusion The decrease in the area of spring tillage did not account wholly for the decline in the numbers of Lapwing nesting on arable land in the study area. It is likely that the decline was due primarily to very low breeding success, which was not compensated by immigration.