AREA-EFFECT IN BREEDING BIRD COMMUNITIES OCCURRING IN AN ARCHIPELAGO OF URBAN HOLM OAK FRAGMENTS (ROME, CENTRAL ITALY)

We carried out a study on breeding bird communities occurring in anarchipelago of 32 holm oak fragments in an urbanized landscape (Rome,
central Italy). The log-transformed species-area relationship is
comparable with other ``insular{''} situations obtained from analogous
mainland fragmented landscapes. We observed a quick decrease of species
number when area size is lower than 2 hectares, with a significant
threshold at 1 ha, unlike rural areas in which a quick species decrement
occurs on a higher area size range (< 10 hectares). Species appear
differently sensitive to area size of the fragments with significant
responses in Dendrocopos major, Aegithalos caudatus, Sitta europaea,
Parus major, Certhia brachydactyla and Fringilla coelebs. Considering
the recreational role of the biodiversity for human populations
inhabiting large metropolitan areas, the threshold in size (about 1 ha
in fragment area) evidenced in this study may be useful for urban park
management strategies.