Purger et al. (2012) Polish Journal of Ecology

Purger, J. J., Mužinić, J., Purger, D. (2012): Survival chances of ground nests in a meadow habitat: a case study in Vrana Lake Nature Park (Mediterranean region, Croatia). Polish Journal of Ecology 60 (1): 247-252.

Abstract

The number of ground-nesting bird species in meadows, one of the most vulnerable habitats in the ornithological reserve of Vrana Lake Nature Park has decreased in recent decades. Nest survival rates were investigated in meadows and reed beds using nest predation experiments in late March and in May 2005. Predators damaged 18% of the 50 artificial nests placed in the pasture meadow habitat in March and 22% in May. Daily survival rate of nests were found to be similar in March (97%) and May (96%). In May, 64% of 25 nests located in the reed bed were discovered by the predators, with the daily survival rate of nests (90%) being significantly lower than that of nests in the nearby meadow. The results suggest that the reasons for the decreasing number of nesting bird species may be – instead of the pronounced presence and activity of predators in the area – the shrinkage of meadow area, the lack of buffer zone, the proximity of agricultural lands, and disturbance caused by intensive grazing.

Keywords

artificial nest, predation, survival rate, threats, Vransko jezero

Ludwig et al. (2012) Acta Oecologica

Martin Ludwig, Hella Schlinkert, Andrea Holzschuh, Christina Fischer, Christoph Scherber, Alfréd Trnka, Teja Tscharntke, Péter Batáry (2012): Landscape-moderated bird nest predation in hedges and forest edges. Acta Oecologica 45: 50–56.

http://dx.doi.org/10.1016/j.actao.2012.08.008

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