Winter density and habitat preferences of three declining granivorous farmland birds: The importance of the keeping of poultry and dairy farms

Populations of granivorous farmland birds have dramatically declined during recent decades in many European countries. Winter conditions and consequently, survival rates of farmland bird species during this critical period, are considered as one of the main causes of this negative trend. However, the importance of different habitat structures and connected food sources for successful overwintering in bird species has gained little attention so far in the Czech Republic. In this study we aimed to examine the role of habitat composition and food availability on winter distribution and abundance of three declining sedentary and granivorous bird species. During the winters 2009–2014, 149 villages in the Czech Republic were monitored for distribution and density of three farmland seed-eaters. House Sparrow was the most dominant species (88.6% of villages occupied; 4.32 ± 4.67 ind./100 m of transect), followed by Tree Sparrow (67.1% villages occupied; 1.83 ± 3.53 ind./100 m of transect) and Collared Dove (65.8% villages occupied; 0.72 ± 1.51 ind./100 m of transect). Occurrence of House and Tree Sparrow was significantly affected by the number of instances of poultry keeping. In both species, occupied villages showed a higher number of instances of poultry keeping. We did not find any such significant relationship for Collared Dove. Density of House Sparrow was significantly higher in villages with dairy farms, but we failed to find this relationship for Tree Sparrow and Collared Dove. Habitat preferences were similar for all three studied species. They positively responded to the proportion of shrubs/trees, the keeping of poultry, dairy farms and they avoided houses, arable land and grasslands. We conclude that poultry keepings and dairy farms can be important for studied species during the winter since they offer high food availability and good protection against predators. This suggestion is supported by the fact that long-term population decline has coincided with a long-term reduction in the keeping of poultry and dairy farms in the Czech Republic during the last 50 years.