BIRD DIVERSITY AND OCCURRENCE OF BAMBOO SPECIALISTS IN TWO BAMBOO DIE-OFFS IN SOUTHEASTERN PERU

A post-flowering die-off of bamboo in an established bird-census plot afforded us an opportunity to investigate the response of bamboo-dwelling birds to a natural transformation of their habitat. In 1984 and 1985 SR and JT generated spot maps for an 80-ha plot in terra firme forest near the Cocha Cashu Biological Station, Manu National Park, Peru. Two mapped bamboo patches in the plot totaled approximately 30 ha. In 2001 and 2002, the bamboo flowered and died. In 2009, IS revisited the plot and generated spot maps for the former bamboo patches and adjacent forest. By 2009, trees had grown up in the erstwhile bamboo patches, creating stands of second growth surrounded by mature forest. Twelve species of bamboo specialists were no longer present but almost no new species had invaded. We conclude that the maintenance of high bird diversity in western Amazonian forests does not depend on the spatial heterogeneity caused by dying off of bamboo. This result contrasts with, but does not contradict, previous research demonstrating the importance of some disturbances such as treefalls opening gaps to avian biodiversity in neotropical forests. A few bamboo specialists, including the Brown-rumped Foliage-Gleaner (Automolus melanopezus), Goeldi's Antbird (Myrmeciza goeldii), Flammulated Pygmy-Tyrant (Hemitriccus flammulatus), and Dusky-tailed Flatbill (Ramphotrigon fuscicauda), persisted in the die-offs. Their choices of microsites suggested that vegetation structure rather than plant-species composition is an important determinant of habitat suitability for these specialists.