Birds of a central São Paulo woodlot: 1. Censuses 1982-2000

Abstract

Some 263 birds were recorded near and in a 230-ha patch of semideciduous forest in cane fields of central São Paulo, Brazil. Subtracting 67 open-area species, 22 of marshes or creeks, 10 vagrants and 12 recorded later, 152 forest and border species were recorded in 1982-86, much like what was observed in a similar woodlot near Campinas. Both woodlots lost species gradually over the years. Some birds avoided hard cane-field edges, preferring soft bushy edges. Of open-area species, 22 seemed to have disappeared by 1997 due to earlier high El Niño rains or rare permanently open habitats in the sugar cane; 17 new species were mostly nocturnal ones not noted earlier, or occasional visitors. Forest and borders lost 31 species, gaining five of dry regions and one winter visitor. Several migrants from the south appeared only in wet years before recent greenhouse effects, some resident birds were hunted, and canopy hummingbirds were perhaps still present. Dry-forest travel-prone or "metapopulational" species moved their centers of distribution, partly concealing loss of moist-forest diversity.Key words: birds, conservation, greenhouse effect, metapopulations, semideciduous forest, sugar cane. RESUMO Aves de uma mata na região central de São Paulo: 1. Censos 1982-2000Foram listadas 263 aves próximo e dentro de uma mata semidecídua de 230 ha em meio a plantações de cana-de-açúcar, na região central do Estado de São Paulo, Brasil. Subtraindo-se 67 espécies de áreas abertas, 22 de riachos, 10 vagantes e 12 observadas mais tarde, cerca de 152 espécies de mata e de borda foram observadas entre 1982-86, semelhantemente às observadas em uma mata próxima a Campinas. Ambas as matas perderam espécies gradualmente. Algumas aves evitaram as margens "duras" dos canaviais, preferindo as margens "macias" arbustivas. Das espécies de área aberta, parece que 22 desapareceram até 1997, em razão das abundantes chuvas anteriores causadas por El Niño, ou pela raridade de habitats permanentemente abertos nos canaviais; 17 espécies "novas" eram principalmente noturnas que não haviam sido checadas anteriormente, ou visitantes ocasionais. A mata e as bordas perderam 37 espécies, ganhando 5 de regiões secas e 1 visitante de inverno. Vários migrantes do sul apareceram somente em anos chuvosos antes do recente efeito estufa; algumas aves residentes foram caçadas, e os beija-flores das copas talvez estivessem presentes ainda. As espécies de zonas secas, prones à movimentação ou "metapopulacionais", movem os centros de distribuição, camuflando parcialmente a perda de diversidade da mata úmida.Palavras-chave: aves, conservação, efeito estufa, metapopulações, mata semidecídua, cana-de-açúcar.

Territory size of three Antbirds (Aves, Passeriformes) in an Atlantic Forest fragment in southeastern Brazil

“…The pair density of the three species considered here was similar to the other Atlantic Forest Thamnophilidae of similar size (e.g. WILLIS & ONIKI 2001). These authors found P. leucoptera pair density of 0.3 pair/ ha similar to the one found here (0.2 pair/ha).…”

“…Moreover, in the Amazonian Forest Thamnophilidae with smaller body mass than the ones we studied have larger territories (TERBORGH et al 1990). The territory size of six species of Thamnophilidae in Atlantic Forest varied from 0.8 to 3.0 ha (WILLIS & ONIKI 2001). These authors found territory sizes for P. leucoptera (2-3 ha) relatively larger than the one we found, and D. mentalis territory size (0.8 ha) was similar to the one we established.…”

“…In contrast, males of Seiurus aurocapillus (Linnaeus, 1766) (Emberizidae) have low pairing success when defending territories close to forest edges (GIBBS & FAABORG 1990). WILLIS & ONIKI (2001) suggest that birds that defend territories in the border need larger areas, because they cannot move in all directions to find food, but it does not seem to be the pattern for B. flaveolus (DUCA & MARINI 2005) and for the three species studied here.…”

“…GREENBERG & GRADWOHL (1986), reported that despite a moderate turnover of territory owners, territories of other Thamnophilidae were essentially identical from year to year. The turnover of territory owners also was observed for T. caerulescens (WILLIS & ONIKI 2001) and B. flaveolus without change in the territories characteristics (DUCA & MARINI 2005). Several studies have found that territory switching occurs at a low rate in year-round residents (GREENBERG & GRADWOHL 1986, WOODWORTH et al 1999.…”

Diurnal and seasonal variability in bird counts in a forest fragment in southeastern Brazil

“…For a more complete species list, however, crepuscular and early evening counts are also important. Perhaps the remainder of the day should be used for other purposes, such as captures (REMSEN 1994) where a greater capture rate may occur after 12:00 (WILLIS & ONIKI 2001). Nevertheless, should it be necessary to count birds during the dry season, day-long counts may be more productive than morning counts, at least in seasonal forests.…”