English

Swift Apus apus numbers have declined by 47% in the UK in the last ten years. And for the first time, the summer migrant has been added to the amber list meaning it is of serious conservation concern. Swifts spend their life almost entirely on the wing and even feed, sleep and mate in flight. They feed exclusively on insects and only come to land when nesting.

Aerial invertebrate abundance over pasture fields in lowland mixed farmland in southern Britain was more than double that over silage, and more than three and a half times greater than that over cereal fields. Pasture fields also hosted approximately twice as many foraging barn swallows as both silage and cereal fields. Past reductions in the availability of pasture may have reduced the numbers of aerial invertebrates, and may have contributed to barn swallow Hirundo rustica population declines, and possibly those of other aerial insectivores.

The Ortolan Bunting Emberiza hortulana has suffered a general decline across much of Western Europe in recent decades. In Switzerland, only one population remains in sub-Mediterranean shrub-steppe on the south-facing slopes of the Rhone Valley (Valais). We aimed to collect data on foraging ecology of the last Swiss Ortolan Buntings during reproduction. All males showed a disproportionate use of conventional maize fields that had been treated with herbicides, while also exhibiting an avoidance of meadows and riparian vegatation. The observed patterns of habitat use may be driven by unavailability of optimal foraging habitat, with birds being forced to use the best of a poor set of options. Structurally, it was shown that birds foraged in areas with a high proportion of bare ground, as well as moderately dense overhead vegatation. These areas did not support higher arthropod abundance, suggesting that food accessibility rather than food abundance dictated habitat selection.

Breeding and wintering abundance of corn buntings Miliaria calandra in an agricultural landscape of Alentejo (southern Portugal) was assessed in relation to agricultural intensification and other environmental variables during 1994-1997. Bird abundance was lowest in intensively managed farmland in both seasons.

Corn buntings Miliaria calandra have declined by a staggering 83% over the past twenty years, according to a new study of thirty sites in Aberdeenshire and Angus published in Bird Study, the journal of the British Trust for Ornithology. This once common farmland bird, known as the ‘fat bird of the barley’, has suffered as farming methods have intensified.

The corn bunting Miliaria calandra has undergone severe population decline in the Republic of Ireland and other western European countries. By the late 1990s, no corn buntings were known to be breeding in Ireland. The most important factors are thought to be the decline in mixed farming and the loss of temporary grasslands. The use of pesticides may have reduced the availability of invertebrate and seed food supplies.

Corn buntings Miliaria calandra were abundant throughout arable agricultural landscapes in Europe, but have catastrophically declined since the mid 1970s with changes in farming practice and now give serious conservation cause for concern. Corn buntings declined in Denmark during 1976-1993, but (almost unique in Europe) have since increased (by up to 11% per annum) in some areas without specific conservation recovery actions. Based on breeding bird surveys in the mid 1990s, highest corn bunting densities occurred on mixed agriculture in west Denmark (Jylland); the species was rarer or absent in regions of highest arable land cover.

By Kate E. Vincent, Ph.D.
In Britain and parts of northwest Europe, House Sparrow Passer domesticus populations have declined markedly since the mid-1980s. This study focused on factors affecting nesting success and annual productivity of nesting House Sparrows along an urban-suburban-rural gradient centred on the city of Leicester, England. The data presented in this thesis suggest that the abundance of invertebrate prey within home ranges of House Sparrows breeding within suburban and rural habitats limits the quantity and quality of chicks raised to fledging. The combined effects of relatively high rates of chick starvation and low body masses at fledging (and consequently low post-fledging survival) observed in surburban localities are large enough to result in rapid population declines.

Nick Brickle reports on a project to investigate the effect of agricultural intensification on corn buntings Miliaria calandra. The main aim was to test the hypothesis that breeding success was affected by low chick-food availability, caused in part by the use of pesticides. Data from a study site on the South Downs in Sussex showed that corn buntings collected invertebrates for their chicks in areas that received relatively few insecticide and herbicide applications. These areas contained more invertebrates of the types commonly fed to chicks than more heavily sprayed areas. When the abundance of chick-food invertebrates was low close to a nest, breeding success was low. In these conditions chicks were underweight, parents foraged further from the nest and nest failure rate was high. When chick-food invertebrates near the nest were more abundant, breeding success was higher. The relationship between pesticides and food availability, and the relationship between food availability and breeding success, links the corn bunting to other species of farmland birds where pesticide use has been shown to affect breeding success, such as the grey partridge. Similar relationships between pesticides, food and breeding success may occur in some other farmland bird species such as skylarks and yellowhammers.