Efficiency of playback for assessing the occurrence of five bird species in Brazilian Atlantic Forest fragments

Playback of bird songs is a useful technique for species detection; however, this method is usually not standardized. We tested playback efficiency for five Atlantic Forest birds (White-browed Warbler Basileuterus leucoblepharus, Giant Antshrike Batara cinerea, Swallow-tailed Manakin Chiroxiphia caudata, Whiteshouldered Fire-eye Pyriglena leucoptera and Surucua Trogon Trogon surrucura) for different time of the day, season of the year and species abundance at the Morro Grande Forest Reserve (South-eastern Brazil) and at thirteen forest fragments in a nearby landscape. Vocalizations were broadcasted monthly at sunrise, noon and sunset, during one year. For B. leucoblepharus, C. caudata and T. surrucura, sunrise and noon were more efficient than sunset. Batara cinerea presented higher efficiency from July to October. Playback expanded the favourable period for avifaunal surveys in tropical forest, usually restricted to early morning in the breeding season. The playback was efficient in detecting the presence of all species when the abundance was not too low. But only B. leucoblepharus and T. surrucura showed abundance values significantly related to this efficiency. The present study provided a precise indication of the best daily and seasonal periods and a confidence interval to maximize the efficiency of playback to detect the occurrence of these forest species.<br>A técnica de play-back é muito útil para a detecção de aves, mas este método geralmente não é padronizado. Sua eficiência em atestar a ocorrência de cinco espécies de aves da Mata Atlântica (Pula-pula-assobiador Basileuterus leucoblepharus, Batará Batara cinerea, Tangará Chiroxiphia caudata, Olho-de-fogo Pyriglena leucoptera e Surucuá-de-barriga-vermelha Trogon surrucura) foi analisada de acordo com o horário do dia, estação do ano e abundância das espécies na Reserva Florestal do Morro Grande (São Paulo, Brasil) e em treze fragmentos florestais de uma paisagem adjacente. Gravações das vocalizações foram emitidas mensalmente ao amanhecer, meio do dia e entardecer, durante um ano. Para B. leucoblepharus, C. caudata e T. surrucura, o amanhecer e o meio do dia apresentaram-se mais eficientes que o entardecer. Batara cinerea apresentou maior eficiência de julho a outubro. O uso do play-back aumentou o período de maior eficiência dos levantamentos de aves em matas tropicais, comumente restrito ao período da manhã durante a estação reprodutiva. A técnica utilizada foi eficiente na detecção da ocorrência de todas as espécies, salvo quando sua abundância se apresentou muito baixa. Porém, apenas B. leucoblepharus e T. surrucura apresentaram abundância significativa e positivamente relacionada com essa eficiência. O presente estudo proporciona uma indicação precisa sobre o melhor horário do dia e época do ano, assim como um intervalo de confiança, com o intuito de aumentar a eficiência do play-back em detectar a ocorrência dessas espécies

Bandages for wounded landscapes: faunal corridors and their role in wildlife conservation in the Americas

The loss and fragmentation of natural habitats is probably the single greatest threat to the world's biological diversity. Fragmentation has a variety of effects including the isolation of habitat remnants, a sharp increase in the amount of habitat edge and, often, a disproportionate loss of certain habitat types - such as accessible areas on fertile, well-drained soils that are most productive for agriculture (Laurance et al. 1999).\ud \ud Wildlife corridors have been advocated as a strategy to lower extinction rates in fragmented landscapes since at least the 1970s (e.g., Willis 1974; Diamond 1975; Wilson and Willis 1975; Wegner and Merriam 1979). By definition, a wildlife corridor is a linear remnant that differs from the surrounding vegetation and connects patches of similar habitat that were more extensively connected in the recent past (Saunders and Hobbs 1991). It is important to emphasize that corridors are not an artificial feature of the landscape, but are intended to help maintain historical habitat connectivity (Noss 1991; Bennett 1999). By facilitating movements of individuals among habitat remnants, corridors can increase population persistence in two ways. First, the demographic and genetic contributions of immigrants can bolster small, dwindling populations in fragments, providing a buffer against local extinction (Brown and Kodric-Brown 1977). Second, if a fragment population should go extinct, immigrants may eventually recolonize the fragment and reestablish the population