ABSTRACT
This study compares the avian response to low impact selective logging by comparing bird species distribution in control and cut forest during five years, with before and post-harvest samples. Ordination analysis showed that the similarity of the bird community post-harvest was lesser than the similarity of samples before harvest. Moreover, the order of abundances of the 43 most common species changed between before and 3 to 4 years post-harvest in the logged forest. Logging affected capture rates for 20 species, either directly or with an interaction with time. The terrestrial insectivorous and mixed-species flocks were the guilds most affected by logging. Both guilds showed decline, correlated with time, in abundances in cut forest. Obligate army ant followers and arboreal insectivorous did not show differences between cut and control forest, but some species in these guilds showed logging effects, either directly or with an interaction between time and logging. Frugivores also did not show logging effects. Nectarivores increased in both the cut forest and in the control forest. Temporal effects of increase or decline occurred in guilds and in 12 species occurring in the cut and control forest. This result suggests that temporal changes in the cut forest may have resulted from succession and temporal changes in the control forest may have resulted from nearby harvest with 40m³/ha intensity in adjacent forest blocks.
Este estudo compara a resposta de uma comunidade aves à exploração madeireira de baixo impacto através da distribuição das espécies em floresta controle e manejada ao longo de cinco anos com amostragem pré e pós-exploração. O procedimento de ordenação mostrou que a similaridade da comunidade de aves após a exploração madeireira foi menor que a similaridade entre as amostras do período de pré-exploração. Além disso, a ordem das abundâncias das 43 espécies mais comuns foi alterada entre o período anterior à exploração e 3 a 4 anos após a exploração na floresta manejada. A exploração afetou as taxas de captura de 20 espécies, diretamente ou através de uma interação com o tempo. Os insetívoros terrícolas e os insetívoros que seguem bandos mistos foram as guildas mais afetadas pela exploração madeireira. Ambas as guildas mostraram declínio, correlacionado com o tempo, em suas abundâncias em floresta manejada. Insetívoros seguidores de formigas e insetívoros arborícolas não apresentaram diferenças entre a floresta manejada e controle, apesar de algumas espécies dessas guildas terem apresentado efeitos relacionados ao manejo florestal, diretamente ou através de uma interação entre o tempo e o manejo. Frugívoros também não apresentaram efeitos significativos relacionados ao manejo florestal. Nectarívoros aumentaram tanto na floresta explorada como na floresta controle. Efeitos temporais de aumento ou declínio observados em guildas e em 12 espécies ocorreram tanto na floresta controle como na floresta explorada. Este resultado sugere que mudanças temporais na área explorada podem estar relacionadas à sucessão enquanto que mudanças temporais na floresta controle podem estar relacionados à exploração com intensidade de 40m³/ha de parcelas adjacentes.
ABSTRACT
Summary The avian genus Progne (martins) is well known for its tendency to roost in aggregations of thousands of individuals. A concentration of approximately 100.000 Progne modesta (southern martins) with 5.000 P. subis (purple martins) in the Peruvian Amazon city of Iquitos in September 1978 is described, with a history of the species occurance in the area. Up to 250.000 individuals of the two species roosted in the Plaza de Armas of Iquitos from April to mid-August 1978. when trees used as roosting sites were cut in an attempt to drive the birds away. By virtue of a rescue effort to replace the lost perches, 100.000 birds were still found in the plaza in mid-September, the remainder having died or left. In September the birds distinctly preferred the southern quadrate of the plaza, and the significance of this distribution in relation to migratory restlessness is discussed. All birds left the plaza by the first week in October, presumably to fly south to breeding grounds in Argentina, Bolivia and Paraguay.
ABSTRACT
Summary The avian genus Progne (martins) is well known for its tendency to roost in aggregations of thousands of individuals. A concentration of approximately 100.000 Progne modesta (southern martins) with 5.000 P. subis (purple martins) in the Peruvian Amazon city of Iquitos in September 1978 is described, with a history of the species occurance in the area. Up to 250.000 individuals of the two species roosted in the Plaza de Armas of Iquitos from April to mid-August 1978. when trees used as roosting sites were cut in an attempt to drive the birds away. By virtue of a rescue effort to replace the lost perches, 100.000 birds were still found in the plaza in mid-September, the remainder having died or left. In September the birds distinctly preferred the southern quadrate of the plaza, and the significance of this distribution in relation to migratory restlessness is discussed. All birds left the plaza by the first week in October, presumably to fly south to breeding grounds in Argentina, Bolivia and Paraguay.
ABSTRACT
Summary The African finch Estrilda astrild is the only exotic bird other than the pigeon to have successfully colonized central Amazonia. The species distribution in Brasil is reviewed. E. astrild has gained a foothold in Amazonia by exploiting grasses native to its original home in Africa. The species potential for agricultural damage is small unless it adapts to feeding on rice. It appears unlikely that E. astrild will displace any native birds.
ABSTRACT
Summary The African finch Estrilda astrild is the only exotic bird other than the pigeon to have successfully colonized central Amazonia. The species distribution in Brasil is reviewed. E. astrild has gained a foothold in Amazonia by exploiting grasses native to its original home in Africa. The species potential for agricultural damage is small unless it adapts to feeding on rice. It appears unlikely that E. astrild will displace any native birds.