Differences in the intensity of nest predation in the curlew<i>Numenius arquata</i>: A consequence of land use and predator densities?

Abstract

We quantified the intensity of nest predation in the curlew in two arable farmland areas in western Finland, as well as nest-site characteristics associated with nest predation using data on real nests (1995-1997) and artificial nests (1996). Predation on real curlew nests was consistently higher in the area of mixed farm/woodland than in the area of continuous farmland (64% versus 5% of nests depredated, respectively). There was no evidence that any of the measured nest-site characteristics was associated with high risk of nest predation and, therefore, area differences in predation on curlew nests probably were due to differences in predator density and landscape structure between the two areas. Predation on artificial nests was far higher than on real nests (79% versus 31% of nests depredated, respectively), but there was no difference in nest losses between areas. In both areas, the likelihood of predation on artificial nests was highest in the vicinity of forest edges. The majority of identified predators on real nests were mammals, whereas those on artificial nests were birds. As a result, we were unable to use artificial nests to estimate the threat of predation or to reliably identify factors related to predation risk on real nests in this study.