Bird traits and nest stage mediate the effects of nest‐site characteristics on nest survival in cavity‐nesting birds of the humid Chaco

Reproductive success is an important component of life history and population ecology, influenced by factors intrinsic and extrinsic to organisms. In birds, where nest predation is the primary cause of reproductive failure, parent behaviours (e.g. nest visits) can increase nest detection and failure by attracting the attention of predators, but they can also deter predators through high nest attentiveness, active defence or selection of an optimal nest‐site. We examine how reproductive behavioural bird traits and nest‐site characteristics interact to influence nest survival in a taxonomically and functionally diverse assemblage of tree‐cavity nesting birds. In 2016–2019, in the subtropical humid Chaco of Argentina, we monitored 342 nests of 21 species every 1–7 days, collected 2387 hours of observations to summarize seven reproductive behavioural bird traits and measured 11 nest‐site characteristics. We used logistic exposure models to test non‐exclusive hypotheses about how reproductive behavioural bird traits, nest‐site characteristics and interactions among these factors influence daily nest survival during the incubation and nestling periods. Predation caused 90% of nest failures, and both behavioural bird traits and nest‐site characteristics influenced nest survival. During the incubation period, nest survival increased with nest attentiveness (time an adult was present in the cavity) and cavity depth. During the nestling period, survival increased with nest tree diameter, cavity height and cavity depth and decreased with number of trees around the nest tree, nest tree crown contact, feeding frequency and aggressiveness. Survival was high regardless of cavity concealment for birds without feeding synchrony behaviour but decreased with concealment in birds with feeding synchrony behaviour. Trait variation in functionally diverse assemblages can help us understand the cost–benefit scenarios that animals face during breeding events and the diversity of strategies they employ to optimize lifetime reproductive success.