Matthew Hiron

Occurrence of Corncrakes Crex crex in mosaic farmland landscapes in south-central Sweden - effects of habitat and landscape structure

Most studies of Corncrakes have been conducted in grasslands used for hay-cutting, and earlier hay-cutting has been suggested as the main cause of population decline in this species. Less is known about habitat preferences in relation to other land-uses and landscape structure. This paper investigated habitat composition and landscape structure in territories and at random sites in arable fields and meadows in south-central Sweden. Calling Corncrakes preferred sites with tall vegetation, moist ground, and locations close to ditches (55% of territories). Suitable conditions occurred on abandoned unmanaged wet meadows (31% of territories), mown wet meadows (14%), leys (30%) and non-rotational set-asides (15% of territories). Corncrakes avoided annual crops and other crops with short vegetation in the spring. Cutting of vegetation before mid-July was recorded in 21% of the territories and resulted in 100% abandonment of these sites. In contrast to many other ground nesting farmland birds, Corncrakes did not avoid forest edges (42% of territories within 100 m of edges). A strategy to conserve Corncrake populations should focus on maintenance of moist natural and sown grasslands (unmanaged or mown late) with tall vegetation and prevention of succession to woodland. Target areas should be in forested landscapes, because many other meadow birds that are more dependent on management (e.g. yearly mowing or grazing) prefer open landscapes.

Crop damage by granivorous birds despite protection efforts by human bird scarers in a sorghum field in western Kenya

Cereal crop damage from granivorous birds poses a serious food security problem for subsistence farmers in sub-Saharan Africa. In this region, farmers may rely on human ‘bird scarers’ to limit crop damage. Here we report feeding behaviour and crop damage patterns caused by Village Weavers Ploceus cucullatus and African Mourning Doves Streptopelia decipiens during four days in a 0.12 ha sorghum field protected by two full-time bird scarers in western Kenya. Despite the scarers’ efforts, almost 60% of the seed was lost before harvest. Bird abundance was largely determined by the presence of the bird scarers, with seed loss patterns being a function of distance from these people. Throughout the day, an average of 18 weavers (maximum 120) was present on the crop in any five-minute period. The number of mud projectiles thrown at the birds per 15 min showed only minor diurnal fluctuations, further suggesting that seed eaters attacked the crop throughout the day. Village Weaver individuals took an average 16 seeds per visit, whereas dove individuals took 32 seeds (maximum 105 and 455, respectively). Our study illustrates that avian crop pests can be extremely persistent and, even with consistent diurnal bird scaring activity, severely damage a small crop field. Bird scarers need to be active throughout daylight hours and patrol both the centres and edges of fields to create maximum disturbance to foraging seed eating birds. Further research is needed in order to investigate effects of local- and landscape-level land use patterns on the feeding behaviour of crop pests and the effectiveness of crop protection measures.

Species contributions to single biodiversity values under-estimate whole community contribution to a wider range of values to society

A major task for decision makers is deciding how to consider monetary, cultural and conservation values of biodiversity explicitly when planning sustainable land use. Thus, there is a great need to understand just what “valuing” biodiversity or species really means, e.g. regarding how many and which species are important in providing ecosystem services or other values. Constructing ecosystem-level indices, however, requires weighting the relative contribution of species to the different values. Using farmland birds, we illustrate how species contribute to different biodiversity values, namely utilitarian (pest seed predation potential), cultural (species occurrence in poetry), conservational (declines and rarity) and inherent (all species equal) value. Major contributions to each value are often made by a subset of the community and different species are important for different values, leading to no correlations or, in some cases, negative correlations between species’ relative contributions to different values. Our results and methods using relative contributions of species to biodiversity values can aid decisions when weighing different values in policies and strategies for natural resource management. We conclude that acknowledging the importance of the range of biodiversity values that are apparent from different perspectives is critical if the full value of biodiversity to society is to be realised.