Population density and use of grasslands by female Little Bustards during lek attendance, nesting and brood-rearing

Abstract

The Little Bustard (Tetrax tetrax) is one of Europe's most threatened birds, and depends mostly on extensive agricultural and pastoral schemes for survival. Due to the female's secretive behaviour, information concerning female breeding ecology is scarce and restricted to sites with some level of agricultural intensification. Consequently, most advice for improving the habitat for this species is based on male habitat needs alone. The breeding season encompasses three distinct biological phases for females-visiting lekking males, nesting, and brood-rearing-which are likely to result in different habitat requirements. In northern Alentejo (Portugal), we studied how female densities vary during the breeding season and analysed their habitat preferences at different scales during the three phases. Both female and male density varied during the season. Local and regional female densities of 16 and 7.6 females/100 ha, respectively, are among the highest ever recorded for the species. The results of a binary GLM suggest a greater probability for the occurrence of nests in larger grassland fields with a vegetation height under 42 cm. Nests were also located preferentially in the proximity of displaying males. Female micro habitat requirements varied significantly throughout the breeding season. Vegetation heterogeneity in larger grassland fields is likely to play an important role in providing adequate habitat for females throughout the whole breeding season. Large grassland fields should, therefore, constitute a management priority in key breeding sites for the species. © 2013 Dt. Ornithologen-Gesellschaft e.V.