Open-Habitat Birds in Recently Burned Areas: the Role of the Fire Extent and Species’ Habitat Breadth = Aves de medios abiertos en áreas quemadas recientemente: la importancia de la extensión del fuego y la amplitud de hábitat de las especies

Abstract

To evaluate the occurrence of open-habitat and steppe-land bird species in Western Mediterranean burned areas and to assess the role of the extent and location of the fire on species richness and composition. At the species level, the relationship was explored between habitat breadth, distribution extent and the ability to occupy recently burned areas. Location: Iberia and Southern France Methods: Fieldwork and bibliography were assembled to obtain breeding bird inventories for 21 burned areas, mostly large wildfires (135- 23,800 ha). The sampling effort was standardized in relation to the area in the 11 fire locations surveyed using transects. Results: Single burned areas contained 0 to 15 open-habitat species (mean = 7.6), and in all the areas combined there were 22 species, including 17 with an unfavourable conservation status in Europe. The most frequent were Carduelis cannabina, Lullula arborea, Alectoris rufa, Oenanthe hispanica and Emberiza cia, but characteristic steppe-land birds such as O. leucura, Calandrella brachydactyla and C. rufescens also bred in particular burned areas. After controlling for the extent of the species range in the Spanish distribution Atlas, passerine occurrence in burned areas was positively related to the species’ habitat breadth in a gradient of unburned habitats. Cluster analysis separated a species-poor group of fire locations from a species-rich group, and showed that some neighbouring areas had a similar species composition. However, there was no spatial autocorrelation between burned areas, and species composition was correlated with the fire extent (Mantel test). Species richness tended to increase with increasing fire area. From the regression equation 5, 9, 12-13 and 16-17 open-habitat species may be expected to occur in burned areas of 100, 1000, 10,000 and 100,000 ha, respectively. Conclusions: This study stresses the importance of biogeographical constraints on colonisation of new habitat patches created by disturbances. The extent of the fire rather than the proximity between burned areas influenced species richness and composition of open-habitat birds in recently burned areas. The best post-fire colonisers were generalists regarding habitat structure. The role of large wildfires in the conservation of threatened open-habitat birds seems to be significant and merits further study