It has been shown that the switch from extensive agricultural practices to cultivating crops with tall and dense sward is among the major agents negatively affecting farmland bird abundance and species richness. As most of our knowledge is based on studies from Western Europe, we counted skylarks in three Central European regions with different agricultural histories and practices, Eastern Czech Republic, Western Germany and Central Poland, to analyse factors affecting its abundance.
Marked regional differences were observed in skylark abundance, being higher in Poland than in Czech Republic and Germany. The highest skylark abundance in Poland is consistent with the long-term dominance of extensive farmland management. In contrast, skylark abundance was slightly lower in Czech Republic than in Germany with higher agricultural intensity. Therefore, agricultural intensity is most probably not the sole driver of regional differences in farmland bird abundance.
Skylark, photo by Tomáš Bělka, birdphoto.cz
In all regions, skylark abundance decreased with growing sward height. Skylarks were more abundant in cereals, especially in those sown in spring, than in other crop types, especially the oilseed rape. The importance of cereal crops for skylarks may be related to the habitat structure resembling the skylarks original steppe habitats. Low abundances found in oilseed rape are in line with the fact that this crop has an extremely dense and high sward during the most of season.
Interestingly, study sites with small-sized fields hosted a slightly lower number of skylarks than sites with larger fields. Skylarks require extensive open landscape without marked vertical and boundary structures (more frequent in small-sized fields), perhaps as a precaution against predation as nests in proximity to field boundaries experience higher rates of predation.
We recommend that (i) extensive farming should be maintained and supported. Since it is less profitable for farmers and may be abandoned in the near future, there is an urgent need to develop a system of mechanisms to make extensive farming more competitive. (ii) Cereals should be preferably cultivated over oilseed rape, an energy crop with uncertain benefits to wildlife. Simultaneously, (iii) spring-sown cereals should be preferred over autumn-sown. These two habitats should have patchy distribution to provide patches of the more suitable spring-sown cereals within the matrix of the less suitable autumn-sown cereals. (iv) Where managing for skylarks, the interventions are best situated away from marked boundary structures or areas of intense disturbance. Finally, (v) management options should carefully consider landscape composition and seasonal changes of crop attributes.
Citation: Koleček, J., Reif, J. & Weidinger, K. 2015. The abundance of a farmland specialist bird, the skylark, in three European regions with contrasting agricultural management. Agriculture, Ecosystems and Environment 212:30-37.
A PDF copy can be obtained from the authors: j.kolecekgmail.com