Local migrations
In Costa Rica frugivorous and nectivorous bird species must be more mobile then insectivorous species to take advantage of peaks of flowering and fruiting that change with the season and the zone. In general in the second half of the year when in Costa Rica the middle and higher altitudes are often drenched by chilling rains resident birds of many kinds tend to descend to warmer, drier levels where there food may be more abundant. During the first month of the following year when the weather improves these species will return upward. Examples of species that are local altitudinal migrants are Three-wattled Bellbird, Resplendent Quetzal, Red-headed Barbet, Silver-throated Tanager and several species of Hummingbirds.
