Nest sites, nest depredation, and productivity of avian broods in a primeval temperate forest: do the generalisations hold?

Data on nest success and brood productivity of three ground‐nesting, three canopy‐nesting and four hole‐nesting (non‐excavator) passerines were gathered in a primeval lowland temperate forest (Bialowieza National Park, E Poland). Natural holes were superabundant and the birds had to cope with a heavy pressure of a diverse assemblage of nest predators. We tested whether in such conditions nesting in holes is more productive, and whether nesting on the ground is most risky, as expected from some earlier generalisations. The nesting success varied significantly across the nest types. As predicted, the success of hole‐nesters (51–74%) and their brood productivity were the highest. Contrary to expectations, the ground‐nesters (27–40%) did not breed less successfully than the canopy‐nesters (22–33%). Nest predators, responsible for 64–94% of nest losses in individual species, were the major cause of the differences among nest types. The Bialowieza results confirm the long‐held view that holes tend to be the safest breeding places, but lend no support for the idea that nesting on the ground is more dangerous than in tree crowns.