Habitat use and foraging parameters of breeding Skylarks indicate no seasonal decrease in food availability in heterogeneous farmland

Reduced food availability during chick raising is a major driver of
farmland bird declines. For the Eurasian Skylark (Alauda arvensis), food
availability is determined by various factors (i.e., arthropod
abundance/diversity, accessibility of the vegetation, distance to foraging
sites). In modern farmland, it is supposed to decrease over the breeding
season due to less penetrable vegetation. We explored foraging habitat
selection by chick-raising Skylarks with a focus on the seasonal dynamics
of habitat use and food availability. We investigated i) habitat selection
concerning prey biomass/diversity, vegetation cover, and distance to
foraging sites, ii) the overall and seasonal habitat use, and iii)
seasonal developments of foraging parameters (e.g., the feeding frequency)
as indicators of food availability. We collected data on foraging habitats
and foraging parameters of chick-raising Skylark pairs at 51 nests from a
Central European population in 2018 and 2019. Prey biomass/diversity and
vegetation cover were measured for all habitats around 42 of these nests.
As revealed by multivariate and compositional analyses, Skylarks mainly
selected foraging habitats based on the proximity to nests. The most
frequent habitats within home ranges could not be ranked according to an
overall importance for foraging and their use partially changed over time.
The feeding frequency increased throughout the breeding season, while
other foraging parameters did not show significant changes. In contrast to
our expectations, our data indicated therefore an increase, not a decrease
in food availability in the late breeding season. This also implies that
the habitat use was constantly suitable to raise offspring. We interpret
this to be a consequence of the heterogeneous farmland composition of the
study area that enabled Skylarks to establish a diverse home range and to
benefit from synergetic effects of neighboring habitat types. Thus, our
findings provide support for the high importance of crop diversity in
Skylark conservation.