Fruits and the Ecology of Resplendent Quetzals

Resplendent Quetzals (Pharomachrus mocinno) are typically termed "specialized" fruit-eating birds, although there are few data describing the breadth of their diet or the characteristics of the fruits they select. In fact, there is no general consensus about the meaning or consequences of being a fruit specialist. In the lower montane forests at Monteverde, Costa Rica, quetzals feed on a minimum of 12-18 species of fruits at most times of the year and on an annual total of at least 41 species. Although their diet includes the watery, small-seeded berries of many second-growth plants, they depend mostly on the large drupes of about 18 species in the laurel family (Lauraceae). The phenologies and habitat distributions of the Lauraceae appear to dictate the timing and direction of seasonal movements by quetzals. Mutual dependence and, possibly, general coevolution between quetzals and the lauraceous trees whose seeds they disperse are suggested by the birds' morphology, distribution, behavior, and life history. Nestling quetzals are brought entire fruits as early as the second day after hatching. Thereafter, they consume gradually increasing amounts of fruit, but, even immediately before they fledge, most of their diet consists of insects, snails, and lizards. Brooding drops off rapidly by the time chicks are 9 days old. Considerable variation in brooding duration, parental sex roles, and nestling diet exists between nests, however, and apparently between clutches. Adults take far less time to deliver fruits to nestlings than to deliver insects or lizards, which reflects the relative ease of "capturing" ripe fruits (as opposed to animal prey) during the breeding season. The male parent delivered significantly more insects and food items in general than did the female at a first-clutch nest but not at a second-clutch nest. Several Central American montane reserves have been established to protect populations of quetzals, the national symbol of Guatemala and an important tourist attraction throughout the Isthmus. Unfortunately, the reserves tend to be too small and to include only a limited representation of critical habitats. If other Central American quetzal populations are similar to Monteverde's, the birds must migrate to different habitats as the availability of ripe fruits fluctuates between seasons or years. Once reserves become isolated by deforestation, they will fail to prevent local extinction of quetzals.