and predators on the survival of open passerine nests

1. A simple model of relative effects of parental behaviour (parents present vs. absent) and nest concealment on probability of nest predation was evaluated by measuring survival of paired natural /artificial nests of four open nesting passerines over 3 years. 2. The ratio of rodent to corvid predation (i) decreased from yellowhammer (small eggs, ground/near ground nests) through blackcap (small, shrub) to song thrush and blackbird (medium sized, shrub/subcanopy); (ii) was highest in years when rodent abundance peaked – this effect was clear in yellowhammer, detectable in blackcap, but not found in thrushes. An inverse relationship was found between mean annual nest sur-vival and abundance of the major nest predator for each species. Predators differed between poorly (corvids) and well-concealed (rodents) nests in blackcap. 3. The effects on nest survival differed among species, including: positive effect of parental behaviour combined with neutral effect of concealment (thrushes); independ-ent positive effects of behaviour and concealment (yellowhammer); neutral effect of behaviour combined with positive effect of concealment (blackcap). These patterns are consistent with hypothesis that relatively larger species with conspicuous nest