Wesołowski T. 2002. Antipredator adaptations in nesting marsh tits Parus palustris - the role of nest site security. Ibis 144: 593-601.

A proposal that nest predation is the most important selective pressure shaping nest-site use of Marsh Tits was checked in a long-term study (almost 500 nests) carried out in the Białowieża National Park (E Poland) in primeval conditions, where the birds bred in natural holes and their nests were at risk from a variety of predators. It was predicted that predation rates would depend on hole attributes, so that Marsh Tits should use the most secure holes. Predation was responsible for 70% of total nest losses. Predation risk depended on hole attributes. Nests in dead wood were predated significantly more often than those in live wood; nests in old woodpecker holes were predated more frequently than nests in holes of other origin, and nests situated closer to the entrance were more at risk than ones further from it. The entrance size did not influence overall predation risk, but the small entrance size was important in preventing access by larger predators. These differences can account for the very rare use made by Marsh Tits of holes in dead wood or of woodpecker holes, of the fact that they nest in holes with small entrances and relatively far from entrance. It is concluded that the patterns of nest-site use found in this species are best explained as anti-predator adaptations, which have evolved and are maintained by the pressure of nest predators. This study also indicates the possible limits of, and constraints on, these adaptations.