Nesting success and nesting height in the critically endangered Medium Tree Finch (Camarhynchus pauper)

When different introduced species across trophic levels (ectoparasite, predator) invade island systems, they may pose significant threats to nesting birds. In this study, we measure nesting height and causes of offspring mortality in the critically endangered Medium Tree Finch (Camarhynchus pauper), an island endemic restricted to Floreana Island on the Galápagos archipelago. Considering all nests at which a male built a nest, sang and attempted to attract a female (N = 222 nests), only 10.4% of nests produced fledglings (5% of nests had total fledging success, 5.4% of nests had partial fledging success). Of the 123 nests chosen by a female, 18.7% produced fledglings and of 337 eggs laid, 13.4% produced fledglings. Pairing success was higher for older males, but male age did not predict nesting success. All nests with chicks were infested with Avian Vampire Fly larvae (Philornis downsi). We attributed the cause of death to Vampire Fly if chicks were found dead in the nest with fly larva...