Impact of cork extraction on birds: Relevance for conservation of Mediterranean biodiversity

Montados are Mediterranean agro-forestry-pastoral systems recognized as an excellent example of balance between socio-economic development and biodiversity conservation. The economic viability of montados dominated by cork oak Quercus suber depends on the extraction of cork (the bark of trees), usually in 9 year cycles, which is mostly used for production of bottle stoppers. This study evaluated the impact of cork extraction on biodiversity, using birds as indicators. Comparing bird assemblages of areas with recently extracted cork and older cork revealed that only two species of bark gleaners and two of bark-foliage gleaners had lower densities in recently debarked areas. Arthropod sampling revealed that, in the first years after cork extraction, the bark has less prey, suggesting that the reduction in bark gleaners densities is a result of the decreased food availability. Focal observations confirmed that the affected species were those that foraged mostly on cork. However, our data demonstrated that bird richness and the density of the majority of species were unaffected by debarking, and that at the landscape level even bark gleaners had potentially stable populations. Pressure from the synthetic bottle stopper industry threatens to render montados economically unviable, and consequently be replaced by land uses much less valuable for biodiversity. Showing that cork extraction is compatible with the maintenance of the great ornithological value of montados, our results confirm that it is an economic activity that should be promoted for the benefit of biodiversity. (C) 2011 Elsevier Ltd. All rights reserved.