Palm snags are a critical nesting resource for woodpeckers in an urbanized tropical region

Abstract

Critical resources for birds nesting in cities can support populations in spite of the challenges imposed by urbanization, and the identification of such resources can shed light on how species are able to adapt to novel environments. In the case of woodpeckers, these resources also support the conservation of secondary cavity-nesters. Woodpecker nesting has been well-studied in temperate regions, including within urban areas, but in subtropical and tropical regions, less is known. Here we ask what types of trees and what habitats woodpeckers use most, and which species of woodpeckers create the most nest cavities. We recorded information from 967 woodpecker nest trees in the region surrounding Miami, Florida, USA, which contained 1864 nest cavities excavated by four woodpecker species. Palm trees were used more than all other tree categories, and royal palms (Roystonea regia) were the most-used species overall. Woodpeckers preferentially excavated palm snags in every habitat where they were available and three of the four woodpecker species used palms snags over all other categories of trees. Red-bellied Woodpeckers (Melanerpes carolinus) were the most prolific cavity excavators, creating 78.1% of holes. Remnant patches of two native forest types contained the highest densities of woodpecker nest trees. We found a higher density of nest trees in moderately-developed suburban areas than either rural, agricultural areas or in the highly-developed urban core. We consider how these results can inform conservation efforts in the developing tropics, and especially within similar urbanizing environments in the nearby Caribbean.