Abstract
Landscape-scale agricultural intensification has caused severe declines
in biodiversity. Hedges and forest remnants may mitigate biodiversity
loss by enhancing landscape heterogeneity and providing habitat to a
wide range of species, including birds. However, nest predation, the
major cause of reproductive failure of birds, has been shown to be
higher in forest edges than in forest interiors. Little is known about
how spatial arrangement (configuration) of hedges affects the avian nest
predation. We performed an experiment with artificial ground and
elevated nests (resembling yellowhammer and whitethroat nests) baited
with quail and plasticine eggs. Nests were placed in three habitat types
with different degrees of isolation from forests: forest edges, hedges
connected to forests and hedges isolated from forests. Nest predation
was highest in forest edges, lowest in hedges connected to forests and
intermediate in isolated hedges. In the early breeding season, we found
similar nest predation on ground and elevated nests, but in the late
breeding season nest predation was higher on ground nests than on
elevated nests. Small mammals were the main predators of ground nests
and appeared to be responsible for the increase in predation from early
to late breeding season, whereas the elevated nests were mainly
depredated by small birds and small mammals. High predation pressure at
forest edges was probably caused by both forest and open-landscape
predators. The influence of forest predators may be lower at hedges,
leading to lower predation pressure than in forest edges. Higher
predation pressure in isolated than connected hedges might be an effect
of concentration of predators in these isolated habitats. We conclude
that landscape configuration of hedges is important in nest predation,
with connected hedges allowing higher survival than isolated hedges and
forest edges.
Highlights
► We performed an experiment with artificial nests in hedges and forest
edges. ► Connected hedges allowed higher survival than isolated hedges
and forest edges. ► Nest predation on ground and elevated nests was
similar in early breeding season. ► In late breeding season nest
predation was higher on ground than on elevated nests. ► Landscape
configuration of hedges is important in nest predation.
Keywords
Artificial nest, Elevated nest, Ground nest, Hedgerow, Mayfield survival rate, Plasticine egg
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