Distribution and abundance of hole-nesting birds in Mediterranean forests: Impact of past management patterns on habitat preference

Abstract

This study explores the relative abundance of hole-nesting birds in four Mediterranean forest types, each of which has undergone different patterns of forest management. Nine species were sampled in 24 study plots, to compare cork oak forest, Turkey oak forest, holm oak forest and pine plantation. The abundance of hole-nesters was greater in cork oak forest and Turkey oak forest. Three species were most frequently detected: Great Tit (Parus major), Blue Tit (Cyanistes caeruleus) and Nuthatch (Sitta europaea). Bird abundance was significantly lower in holm oak forest, particularly in the cases of Great Spotted Woodpecker (Dendrocopos major), Green Woodpecker (Picus viridis), Nuthatch and Short-toed Treecreeper (Certhia brachydactyla). The Great Spotted Woodpecker showed a positive correlation with the abundance of three secondary cavity nesters: Nuthatch, Short-toed Treecreeper and Starling; in contrast, Green Woodpecker showed a negative correlation with Starling. Habitat structure varied significantly among forest types, especially the mean and maximum tree height, these being lower in holm oak forest. The Great Spotted Woodpecker proved to be a good indicator of less disturbed woodlands. In fact, maximum tree height turned out to be a significant and positive explanatory variable for woodpecker abundance. We consider that intensive coppicing and timber management in holm oak forest during the 20th century widely affected trees' age-profile, with consequences for their suitability for woodpeckers and other hole-nesting birds. To monitor the response of hole-nesting birds to forest management in terms of abundance, we propose the use of the great spotted woodpecker as an indicator species.