The author investigated feeding behavior, bird activity on and seed dispersal of two sympatric Neotropical rain forest trees, Guarea macrophylla and Trichilia quadrijuga In Manu National Park, Peru. The numbers of individual visitors, visiting species, and seeds removed were directly correlated to the available fruit crop for each plant species. Of 18 bird species which consumed Guarea fruits, only Swainson’s Thrush (Catharus ustulatus), Sulphur-bellied Flycatcher (Myiodynastes luteiventris), Blue-crowned Manakin (Lepidothrix coronata), and Band-tailed Manakin (Pipra fasciicauda) consistently visited and dispersed its seeds. Of three bird species which consumed Trichilia fruits, only Band-tailed and Roundtailed Manakins (P. chloromeros) regularly visited and dispersed its seeds. Variance in the time spent at fruiting trees across and within bird species was high. Most bird activity occurred between 07:00 h and 10:00 h. The number of ingested pulp units per visit ranged from zero to six depending on the bird. Few seeds were dropped under the parent tree.
Guarea macrophylla Photo: www.ib.usp.br
Despite having similar fruits, 18 species in 6 families removed G. macrophylla pulp units, whereas only three piprids removed T. quadrijuga fruits. Species feeding varied from the small 9 gram manakins to the much larger 72 gram White-necked Thrush. Guarea was fed on by migrant as well as resident species. The preference for Guarea fruits compared to those of Trichilia highlights the need for observational study in determining trees important as avian food resources. Such information will become invaluable as reserve sizes decline hence floral enrichment efforts become desirable to maximize food resource availability.
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