Seasonal abundance and breeding habitat occupancy of the Orinoco Goose (Neochen jubata) in western Brazilian Amazonia

作者：Endo Whaldener^*; Haugaasen Torbjorn; Peres Carlos A

来源：Bird Conservation International, 2014, 24(4): 518-529.

DOI：10.1017/S0959270914000173

The Near-threatened Orinoco Goose Neochen jubata is a poorly known South American sheldgoose with a declining population and range distribution. In this study, we surveyed the Orinoco Goose population along the middle reaches of the Rio Jurua, western Brazilian Amazonia, and its first-order tributaries. We quantified the seasonal abundance of geese, pinpointed their approximate breeding season, and examined their habitat associations and the potential effects of human activities on their abundance. Hunting by local villagers was also monitored to assess the offtake rate of this species. Orinoco Goose occurrence in the region was highly seasonal and restricted to the dry season. We estimated a mean dry-season encounter rate of 7.18 2.45 adult individuals per 4-km section along this river. Immature individuals were seen along the river margins from August to December. The species showed a strong preference for sandy beaches and was primarily restricted to the main river channel, with few individuals occurring along tributaries. The encounter rate of this species was also significantly related to fluvial distance from the municipal urban centre and to the level of protection from hunting. Hunting of Orinoco Goose was reported in 12 of the 26 villages monitored. The seasonal appearance of the Orinoco Goose in the region indicates that this is a migratory population. Our study indicates that strict protection of the river margins, and sandy beaches in particular, along the main river channel is likely to be positive for the conservation of this species along the Rio Jurua. However, further knowledge of migration routes is critical for effective protection of both breeding and non-breeding populations. %26lt;br%26gt;Resumo O quase-ameacado pato-corredor Neochen jubata e um anatideo sul-americano pouco conhecido e com uma populacAo decrescente devido, principalmente, a intensa pressAo de caca. Neste estudo, nos realizamos censos populacionais de patos-corredores ao longo do medio curso do rio Jurua, Amazonia Ocidental Brasileira, e de seus tributarios de primeira ordem na regiAo. Nos quantificamos a abundancia sazonal de patos-corredores, definimos a epoca de reproducAo e investigamos as associacoes de habitat e as potenciais influencias de atividades humanas em sua abundancia. Atividades de caca em comunidades locais foram tambem monitoradas a fim de avaliar a taxa de abate da especie. A ocorrencia da especie na regiAo foi acentuadamente sazonal e aparentemente restrita aos meses da estacAo seca. A taxa de encontro de individuos adultos durante essa estacAo foi estimada em 7.18 +/- 2.45 ind/4 km de secAo de rio. Individuos imaturos foram vistos ao longo das margens do rio e tributarios durante o periodo de agosto-dezembro. A especie demostrou uma forte preferencia por praias arenosas e se mostrou basicamente restrita ao canal principal do rio Jurua, com poucos individuos encontrados ao longo dos tributarios. A taxa de encontro da especie foi tambem significativamente relacionada a distancia fluvial do centro urbano municipal e ao nivel de protecAo de caca. A caca de patos-corredores foi registrada em 12 das 26 comunidades monitoradas. A ocorrencia sazonal de pato-corredor na regiAo sugere que essa e uma populacAo migratoria. Nosso estudo indica que regras de protecAo restritas das margens do rio, e, em particular, das praias arenosas, podem ser beneficas para a conservacAo desta especie na bacia do Jurua. No entanto, um melhor conhecimento das rotas migratorias e fundamental para uma protecAo efetiva de populacoes reprodutivas e nAo reprodutivas.

• 出版日期2014-12