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118 Frugivory by birds in Myrsine coriacea (Myrsinaceae) inhabiting fragments of mixedAraucaria Forest in the Aparados da Serra National Park, RS, BrazilAparecida Brusamarello Basler; Eliara Solange Müller and; Maria Virginia PetryDiscuSSIonArea size and its degree of isolation influence speciesrichness and abundance, as well as the colonisation, evolutionand persistence of species in a habitat (MacArthur andWilson 1967, Saunders et al. 1991, Andrén 1994, Turner1996). Other important factors are the layout of the remainingforest fragments and how surrounding areas areused (Saunders et al. 1991, Rodewald 2003). There havebeen an increasing number of studies quantifying theseeffects on bird communities in recent decades (Mooreand Hooper 1975, Galli et al. 1976, Leck 1979, Robbins1980, Blake and Karr 1984, Lynch and Whigham 1984,Harper 1989, Wilcove and Robison 1990, Soulé et al.1992, Thiollay 1992, Hamel et al. 1993).The Rain forest has significant importance in the jointhistory of occupation of the south, not only the territorialextension that was, but mainly by the economic value itrepresented for nearly a century (Klein, 1985). Differentsizes of Araucaria Mixed Forest fragments in the presentstudy are the result of both natural processes of evolutionand human interference. According to Pillar and Quadros(1997), soil water availability may be a limiting factor toforest expansion, thereby explaining the predominance ofgrassland vegetation in the region. However, the grasslandsform a matrix among the forest fragments, which exhibitvery similar flora and fauna richness, despite the distancesbetween them. This indicates that differences in size anddistance are not determinant factors for plant and animaldispersal in this system. It is possible that the local particularitiesneutralise the effect of area size on the species richnessof frugivorous birds. It is important to point out thatthe bird species recorded are altered environment speciesand no specialist species were recorded. Therefore, there isa need to conserve and even restore the fragments.Elaenia species were the most representative regardingboth number of visits and fruit consumption, but aregenerally considered insectivores. In a diet study on thisgenus, Marini and Cavalcanti (1998) discuss its positionin the insectivore guild and conclude that five Elaeniaspecies are highly frugivorous and consume fruit throughoutthe year. Foster (1987) and Poulin et al. (1994) alsocite species from this genus with high fruit consumptionrates. Marini and Cavalcantti (1998) consider Elaeniageneralists with regard to the type of fruit, as they consumediverse sizes, forms and colours of fruits, often fromMyrsinaceae, Moraceae and Melastomataceae. Fransciscoand Galetti (2001) also indicate the genus Elaenia as havingthe greatest relative percentage of fruit consumption.According to Schupp (1993), dispersal efficiency ismeasured by the following factors: the way fruit is handledbefore ingestion, the length of time birds stay on the plant,the number of visits they perform, whether the birds defecateon the mother plant, etc. The present study foundthat all Elaenia species consumed the fruit whole, withoutmashing it. Marcondes-Machado (2002) recorded similarbehaviour for these species on Miconia rubiginosa (Melastomataceae).This bird genus remained a short time on theplant, performed a greater number of visits and was onlyobserved defecating once while feeding on M. coriaceafruits. Based on these factors, E. flavogaster, E. parvirostris,E. mesoleuca and Elaenia sp. can be considered probablepotential dispersers of M. coriacea fruits in the ASNP.Three Emberezidae species from the frugivorousguild were recorded consuming M. coriacea fruit. Thesespecies swallowed the fruit whole, which may be relatedto the small size of the fruit and the thin pericarp (Mez1959). According to Snow (1981), the frugivorous vertebratediet can be described as either specialised or generalised,depending upon the size and nutritional valueof the fruits and seeds offered by plants. Fruits and seedsconsumed by generalist species are typically small andhave very low nutritional value, thereby demonstratingthe close association between plants and dispersers. Platycichlaflavipes, T. rufiventris and T. albicollis (Muscicapidae)also swallowed M. coriacea fruit whole and similarbehaviour for these species has been observed in Rapanea(Myrsinaceae) by Pineschi (1990).Aggressiveness was greater among individuals ofthe same species, which has also been observed in otherfrugivory studies (Leck 1969, Cruz 1974, Foster 1987).Elaenia sp. performed the highest number of agonisticencounters, which was also observed in R. lancifolia byFranscisco and Galetti (2001), who state that intraspecificand interspecific agonistic encounters are a negativefactor to the dispersal process, but in small numbers donot seem to constitute a determinant factor.M. coriacea is a pioneer and abundant species in theedges of clearings and patches of Araucaria Mixed Forestin ASNP (Snow 1976, Howe 1993). The fragment structuresof the forest patches, however, did not impede thebirds to dislodge among patches and disperse the seeds.In this exchange that occurs between the trees, whichprovide the fruit (a nutritional content in the form of afleshy pericarp (Snow 1981, Van der Pijl 1982, Coates-Estrada and Estrada 1988)), and birds, that can consumefruits and disperse their seeds to far from mother-plants,the rates of plant populations are enhanced, rates of seedlingspredation and competition among adult plants arereduced (Janzen 1970 and Connell 1971). Many studiesshow that frugivory by birds and other various animalsmay be important for the management plans and recoveryin tropical forests (Howe 1984).ACKNowledGMENtsWe thank to UNISINOS for the infra-structure support in thelaboratory and field samples; the Conservation Unit of the Aparadosda Serra National Park for field logistics assistance; and our laboratorycolleagues.Revista Brasileira de Ornitologia, 17(2), 2009