Managing water levels on wet grasslands to improve foraging conditions for breeding northern lapwing Vanellus vanellus

Abstract

The widespread drainage of wetlands and grazing marshes has been one of the main drivers of severe reductions in the number and range of breeding waders across Europe. Wader chicks require wet, invertebrate-rich foraging habitats and most agricultural land is now too dry to support sustainable breeding populations. Recent efforts to re-create wet grasslands and improve wader breeding success have focussed on reinstating wet features, in order to provide foraging habitats for chicks. The success of wet feature installation will therefore depend on whether they provide sufficient invertebrate prey for chicks throughout the pre-fledging period. Techniques for re-creating lowland wet grasslands from arable and pastoral farmland are becoming increasingly well-established, and support from agri-environment initiatives is now available for wet feature installation on grasslands. Here we explore the effect of wet feature provision on invertebrate abundance and the growth rates and body condition of northern lapwing Vanellus vanellus chicks, on grazing marshes in eastern England. Wet features supported more than double the biomass of surface-active invertebrates and a greater abundance of aerial invertebrates than the vegetated grazing marsh. Chick foraging rates were also two to three times higher in wet features than in the grazing marsh, as was the estimated biomass intake per food item. At the start of the breeding season, chick condition was unrelated to wet feature provision but late in the season, when water levels were low, chick body condition was significantly higher in fields with footdrain densities of more than 150 m ha-1. Chick condition declined with increasing rainfall, and low growth rates and longer pre-fledging periods in 2007 are likely to have resulted from unusually intense and prolonged summer rainfall. Synthesis and applications. The installation of wet features on grasslands provides valuable foraging locations for chicks, particularly later in the season when these features are likely to be the main source of water available. Predicted changes to the seasonality of precipitation at temperate latitudes means that provision of wet features is likely to be increasingly important for maintaining breeding wader populations. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.