Timing of nest predation events during incubation for six passerine species in the austral Chaco

Abstract

We analysed the temporal occurrence (day–night) and timing of nest predation events during incubation for six common passerine species breeding in austral Chaco, a temperate South American habitat. We recorded time of predation events and incubation parental care activity using temperature sensors (data validated by field observations of nest fate) for 187 nests. The temporal occurrence of 35 predation events (77% during the day and 23% overnight) suggests a predator assemblage likely dominated by diurnal predators. Greater nest parental activity occurred early in the morning (06 00–09 00h) and late afternoon (17 00–20 00h), coinciding with a greater number of predation events. However, the relationship between the number of parental trips to a nest and its incidence on nest predation was not significant. Likewise, for Golden-billed Saltator, with parental activity and predation patterns similar to those of the group of species as a whole, nest parental activity was not significantly related to nest success/predation fate during incubation. Even though patterns of parental activity and predation events throughout the day seem alike, the lack of statistical relationship between such variables casts doubts regarding the influence of nest predation on parental behaviours during incubation in the species studied here.