Combining the seeds from both years, and using only seeds for which the disperser was known, the mean canopy cover at sites of seeds dispersed by bellbirds was significantly lower than of sites of seeds dispersed by all the other species (89 and 96%, respectively; Kruskal-Wallis test: [[chi].sup.2] = 42.7, df = 1, P [less than] 0.001).
Seedlings from seeds dispersed by bellbirds were significantly taller than those at other species' sites (t test = 2.37, N = 38, P = 0.02).
The results illustrate three main points: (1) bellbirds dispersed seeds in a different pattern than the other species; (2) postdispersal seed predation is highest near the parent trees, but is also high everywhere; and (3) the pattern of recruitment is bimodal with a peak near the parent tree in closed canopy forest, as well as another in gaps corresponding to bellbird perches.
Only male bellbirds frequently dispersed seeds to tree fall gaps.
The influence of bellbirds on the pattern of seed fall is shown by the slight increase in the number of seeds 40-65 m from the parent trees (Fig.
Snow (1961, 1970, 1973b) notes that other species of bellbirds (Procnias) preferentially select pe rches on dead trees or branches, or in sparsely vegetated trees.
"A seed that's dispersed by a bellbird has a better chance of surviving as a seedling," says Wenny These seedlings were only half as likely to catch a fungus disease, perhaps because bellbirds perch in relatively sunny spots.
A three-wattled bellbird waggling and booming to impress a female may be the best friend a tropical fruit ever had.
The finding intrigued another bellbird researcher, Nat Wheelwright of Bowdoin College in Brunswick, Maine.
The populations of six endemic species are considered to be decreasing or unknown and are on the list of endangered species of Costa Rica: Black-thighed Grosbeak (Pheucticus tibialis), Three-wattled Bellbird, Black Guan, Black-faced Solitaire, Golden-browed Chlorophonia, and 0range-bellied Trogon (Table 1).
It is also necessary to focus attention on species such as the Orange-bellied Trogon, Black Guan, Three-wattled Bellbird, the Golden-browed Chlorophonia and other Neotropical endemic species whose populations are decreasing.
The Threewattled Bellbird, the Black-faced Solitaire, the Resplendent Quetzal, and the Golden-browed Chlorophonia are known window casualties that are altitudinal migrants.