Mapping bird assemblages in a Mediterranean urban park: Evidence for a shift in dominance towards medium-large body sized species after 26 years

Abstract

We assessed the structure of the breeding bird assemblage in a Mediterranean urban park in 2012, and compared it with data gathered in the same area in 1986. Since 1986, Wryneck ( Jynx torquilla ) territories have disappeared from the study area, while breeding pairs of Green Woodpecker ( Picus viridis ) and the introduced Rose-ringed Parakeet ( Psittacula krameri ) have colonized the park. We observed a significant decrease in density of the Italian Sparrow ( Passer italiae ) and a significant increase in Starling ( Sturnus vulgaris ). At the assemblage level, overall bird densities decreased but total bird biomass increased due to the increase in density of (often cavity-nesting) medium to large body sized species (such as woodpeckers, Rose-ringed Parakeet and Starling). A presumed increase in mature tree availability and in predation by synanthropic species (e.g. crows) may explain the high density and biomass of primary and secondary cavity nesters characterized by medium-to-large body sizes. The decline of Sparrows and Wryneck may reflect the decreasing trend at the continental scale.