Bird community assemblage and distribution in a tropical, urban ecosystem of Puerto Rico

Abstract

Urbanization has profound effects on the presence and distribution of wildlife species. Although numerous studies have been conducted to inform our understanding of the effects of urbanization on wildlife, studies of urban wildlife communities in the tropics are especially rare. Here, we investigated the bird community assemblage and distribution at an urban military installation, Fort Buchanan, located within the San Juan Metropolitan Area on the Caribbean island of Puerto Rico. Using fixed-radius point count surveys and opportunistic encounters, we documented over 1,700 individual birds of 60 avian species across three sampling periods in March, April, and October 2016 (84 surveys over 12 total sampling days). The species occurring at the highest densities in this urban environment were Bananaquit (Coereba flaveola: 4.58 birds/ha), Antillean Grackle (Quiscalus niger: 3.64 birds/ha), Zenaida Dove (Zenaida aurita: 2.25 birds/ha), and White-winged Dove (Zenaida asiatica: 2.12 birds/ha). The birds occurring in the lowest densities were one native, imperiled duck species (Dendrocygna arborea), and several neotropical migrants. Most species were not randomly distributed throughout the site but were instead correlated with particular landscape features or habitat types. For instance, migratory warblers were mostly found in remnant forest patches, while Zenaida Doves were associated with open, grassy areas. As human populations continue to expand and urbanization spreads, it will become increasingly important to conserve critical, but often overlooked wildlife habitat—especially forest patches for migratory birds—within urban ecosystems.