Density and behaviour ofWhinchatsSaxicola rubetraonAfrican farmland suggest that winter habitat conditions do not limitEuropean breeding populations

Abstract

TheWhinchatSaxicolarubetrais anAfro‐Palaearctic migrant undergoing widespread population decline.Whinchats winter inWestAfrica but there are almost no data on their habitat use and behaviour there that may help to explain the cause of this decline. We measured the density ofWhinchats, the habitat characteristics associated with their occurrence on farmland, and the relationships between behavioural and habitat variation on farmland around Jos, central Nigeria, over three winters.Whinchats occurred in many fields harvested in the dry season, the density at three sites varying from 0.03 to 0.43 birds/ha, but they were absent at a fourth site. Whinchats were less likely to be found in farmland without particular crops (e.g. structural stem crops such as maize and millet), with more trees, lower amounts of short vegetation (grass, weeds, crops and crop stubble less than 10 cm in height), and higher amounts of medium vegetation (coverage of vegetation 10–100 cm in height) and litter (dead, unburned, vegetation on the ground). Whinchat abundance in areas of farmland where they were present was independent of most variables considered, but density was higher where there was more short vegetation cover. Foraging behaviour did not vary significantly between farmland habitats. All predictors were consistent between season, years and across sites. The presence/absence model was very poor at predicting presence and there were no strong predictors of abundance or foraging variation. This is consistent with a species well below carrying capacity within its environment so that many suitable areas do not have birds present and there is little aggregation at better sites. Overall,Whinchats were abundant and appeared to have plentiful habitat; densities have probably increased alongside the intensification of agriculture (presence of fallow farmland, short vegetation and structural crops). The results suggest thatWestAfrican farmland in the dry season can support large numbers of Whinchats and that recent population declines in Europe are unlikely to be caused primarily by lack of suitable wintering habitat.