Spatial and temporal analysis of the distribution of forest specialists in an urban-fragmented landscape (Madrid, Spain) -: Implications for local and regional bird conservation

Management strategies for the regional conservation of forest birds sometimes do not consider explicitly their applicability to areas with different degrees of urbanization. I studied the spatial and temporal distribution of forest passerines in wooded parks in the city of Madrid during two consecutive breeding seasons to identify factors relevant to local conservation, and compared these results to previous studies in rural-fragmented forests in central Spain to derive recommendations for local and regional management guidelines. Five independent factors were considered: park size, isolation, density of potential corridors, vegetation structure, and pedestrian rate as an indicator of human disturbance within parks. Species richness and species temporal persistence was positively influenced by park size, shrub and tree cover, number of shrub and tree species, number of thick tree trunks, and negatively by the number of thin tree trunks. Species turnover was negatively affected by park size, such that the temporal persistence of species was enhanced in large parks. The pattern of guild assembly was not random but nested (parks with few species were subsets of progressively richer parks); the accumulation of species being affected mainly by park size and human disturbance, and to a lesser degree by isolation and vegetation structure. With regard to the spatial distribution of individual species, park size and vegetation structure positively influenced five species each, whereas isolation and human disturbance negatively influenced two and one species, respectively. Fragment size and habitat structure were the most relevant factors affecting species richness of forest specialists in both rural and urban fragmented landscapes; therefore, regional conservation strategies to protect these species may also be applicable to urbanized areas in central Spain. However, some specific recommendations should be considered in urban and suburban landscapes: (1) habitat quality ought to be enhanced to meet specific habitat requirements, particularly in large parks; (2) the mechanisms and rates of dispersal of forest birds through the urban matrix should be further studied to improve the movements between regional and local populations; and (3) species-specific variations in tolerance to pedestrians and thresholds levels of human visitation within parks should be determined to minimize human disturbance effects. (C) 2003 Elsevier B.V. All rights reserved.