Habitat selection of cavity‐nesting birds in the Hyrcanian deciduous forests of northern Iran

Abstract

AbstractThe Hyrcanian forests of northern Iran support a great diversity of bird species. Yet, the ecological relationships of cavity‐nesting birds (CNBs), the main components of forest bird communities in this area, remain unknown. We examined the importance of ecological factors in 90 study plots during the breeding season to predict the probability distribution and habitat suitability of primary cavity nesters (PCNs), secondary cavity nesters (SCNs) and weak primary cavity nesters (WPCNs). Ecological factors included forest structure, habitat complexity, geographical attributes and dead tree features. The significant habitat parameters determining the presence‐absence of each CNB species were also determined. PCN richness and abundance were most influenced by the density of larger trees, snags (standing dead trees) and logs (fallen dead trees). The densities of snags, logs and larger trees and the extent of the shrub layer influenced distributions of SCNs. The Eurasian nuthatch (Sitta europaea) was the only WPCN identified, and its distribution was strongly affected by altitude and by larger snags and trees in complex habitats. Our results showed that CNB species could be classified in three groups: (1) species dependent on mature forests, (2) species dependent on younger forests and (3) species adaptable to different forest stages. Overall, snags and logs played vital roles in the habitat preferences of CNB communities as well as in forest structure and complexity.