Low and variable reproductive success of a neotropical tyrant-flycatcher, Chapada Flycatcher (Suiriri islerorum)

The decline of several bird populations has been related to reduced reproductive success. Here we used the logistic-exposure method to model the temporal (age, daily, annual) variation in reproductive success of a neotropical tyrant-flycatcher, the Chapada Flycatcher (Suiriri islerorum), which has been described only recently (2001). We monitored 56 nests, in a reserve in central Brazil, over four seasons from 2003 to 2006. Predation affected 66% of the monitored nests, but varied greatly across years. The probability of daily survival decreased 7% day -1 with the age of the nest and the reproductive success varied greatly between years (16.8, 75.4, 6.7 and 21.4%, 2003-06 respectively). Mean reproductive success (using three analytical methods) ranged from 21 to 25%, but from only 13 to 16% when results from 2004 were excluded. Such low and variable reproductive success is atypical for a neotropical bird. In combination with the small population size and known decline of this population, our findings raise conservation concerns for this isolated population.