No abstract

We studied the avifauna of sun and shade coffee plantations and associated mid‐elevation habitats during the dry season of 1995. The three plantation types (Inga, Gliricidia, and sun) showed high faunistic similarities with each other and were both distinct and depauperate compared to matorral and forest patch habitats. Of all the coffee plantation habitats, Inga shade had the highest diversity. Species associated with wooded vegetation were more common in shade plantations, particularly in Inga. A second census showed a decline in bird numbers that was more pronounced in sun and Gliricidia than in Inga plantations. Overall, differences between the plantation types were small and all coffee plantations were less diverse than traditional coffee farms previously studied in nearby Chiapas, México. The relatively low bird diversity was probably due to the low stature, low tree species diversity, and heavy pruning of the canopy. These features reflect management practices that are common throughout Latin America. The most common species of birds in all coffee plantation habitats were common second‐growth or edge species; more specialized forest species were almost completely absent from plantations. Furthermore, many common matorral species were rare or absent from coffee plantations, even sun plantations with which matorral shares a similar superficial structure. Coffee plantations probably will only be important for avian diversity if a tall, taxonomically and structurally diverse canopy is maintained. We suggest this is most likely to occur on farms that are managed for a variety of products rather than those designated entirely for the production of coffee.

Many avian species persist in human-dominated landscapes; however, little is known about the demographic consequences of urbanization in these populations. Given that urban habitats introduce novel benefits (e.g., anthropogenic resources) and pressures (e.g., mortality risks), conflicting mechanisms have been hypothesized to drive the dynamics of urban bird populations. Top-down processes such as predation predict reduced survivorship in suburban and urban habitats, whereas bottom-up processes, such as increased resource availability, predict peak survival in suburban habitats. In this study, we use mark-recapture data of seven focal species encountered between 2000 and 2012 to test hypotheses about the processes that regulate avian survival along an urbanization gradient in greater Washington, D.C., USA. American Robin, Gray Catbird, Northern Cardinal, and Song Sparrow exhibited peak survival at intermediate and upper portions of the rural-to-urban gradient; this pattern supports the hypothesis that bottom-up processes (e.g., resource availability) can drive patterns of avian survival in some species. In contrast, Carolina Chickadee showed no response and Carolina and House Wren showed a slightly negative response to urban land cover. These contrasting results underscore the need for comparative studies documenting the mechanisms that drive demography and how those factors differentially affect urban adapted and urban avoiding species.