Exotic trees fail as a support for red-crested cardinal (Paroaria coronata) nests in a native forest of east-central argentina

Abstract

Different tree species offer birds different types of bases for building the nests; those with thorns have been reported as important structural supports to contain and protect the nest from predators. We eva-luate whether the tree used for nest support of the Red-crested Cardinal (Paroaria coronata) influences the du-rability and viability of the nests. Because the native forests of east-central Argentina are heavily altered by anthropic activity and coexist with a large number of exotic tree species, we assessed whether the frequency of broken-down nests before completing the nesting cycle varied between native and exotic trees. We monitored 207 nests in natural areas (all built on native trees) and 22 in modified habitats (seven on native trees and 15 on exotic trees). Among the nests built on native trees, the frequency of broken-down nests was lower in the Spiny Hackberry (Celtis ehrenbergiana) than in Scutia buxifolia and Schinus longifolius trees. Although all of them have thorns, we attribute this result to the tangled and zigzagging arrangement of C. ehrenbergiana branches that offer better support for the nests. On the other hand, the frequency of broken-down nests before completing the nesting cycle was higher in exotic trees, which raises concerns about the negative effect of the presence of exotic trees in the breeding areas of the Red-crested Cardinal. Considering the continuous invasion and expan-sion of exotic trees in these remnants of native forests, we suggest the authorities take measures to avoid new introductions and to control the progress of those that are already expanding, such as the worrying invasive tree Gleditsia triacanthos.