Zur Bedeutung von Kleinstrukturen im Ackerland: Bevorzugt die Feldlerche (Alauda arvensis) Störstellen mit Kümmerwuchs?

Breeding season responses of Skylarks Alauda arvensis to vegetation structure in set‐aside (fallow arable land)

“…A very high percentage of bare ground was also unsuitable for Skylarks ( Fig. 1) and thus our data compare favourably with values of 50% bare ground in wildflower strips (Wiebel 1998), in arable fields (Schon 1999) and in winter grassland . Differences between studies probably reflect a trade-off between foraging access and vegetation cover (which supports invertebrate prey; e.g.…”

Suitability of patches and in‐field strips for Sky LarksAlauda arvensisin a small‐parcelled mixed farming area

“…and undrilled patches, both with the aim of creating vegetation heterogeneity, reducing vegetation density and thereby adjusting it to Sky Lark foraging and nesting requirements. In the late 1990s, it was found that Sky Larks use microhabitat structures in cereal fields when the vegetation reaches a critical height (Odderskaer et al 1997, Schön 1999 or, when no microhabitats are available, that they are forced to nest on tramlines and field borders where predation rates are almost doubled (Donald 2004). Researchers in the UK have therefore developed in-field measures to open up the sward structure of winter wheat (SAFFIE project, Morris et al 2003Morris et al , 2004.…”

Territory density of the Skylark (Alauda arvensis) in relation to field vegetation in central Germany

“…Reasons for avoiding fields with tall vegetation and coverage of over 90 % might be the decreased orientation possibility for Skylarks (Pätzold 1983) or the hindered ground locomotion (Jenny 1990b, Odderskaer et al 1997). By the same token, small open patches in the fields and places with stunted growth have a positive effect on the density (Schläpfer 1988, Odderskaer et al 1997, Schön 1999). Other factors which might also have an influence are food availability within the territories (Jenny 1990a) and the dryness of habitats (Pätzold 1983).…”

“…Among the crops, spring and winter cereals seemed to be most important for early broods (Jenny 1990b, Schön 1999); and sugar beets, sunflowers or spring cereals for later broods in summer. Winter cereals and winter rape were the only crops with vegetation coverage in early spring, also important as feeding habitats.…”

“…This was the result of a certain tolerance by the farmers of neglected remaining areas (George 1995). The frequent occurrence of open patches within the fields, together with the less intensive use of fertilisers and pesticides before German re‐unification (George 1995), might be factors behind the higher density (Jenny 1990c, Schön 1999). In contrast, two factors might be crucial to the future success of Skylarks in eastern Germany: first, the proportion of fields with lucerne or grass crops has decreased recently (George 1995), and these used to be suitable breeding and feeding habitats (Pätzold 1993; this study); second, the percentage of winter cereals is greater than it was before 1990, a situation offering fewer suitable breeding habitats in summer and a low diversity of arthropods as food (Jenny 1990a, George 1995).…”