Assessing habitat-related disturbance in bird communities: Applying hemeroby and generalism as indicators

We tested the application of the concept of hemeroby and generalism at community level, on a set of birds occurring in various habitats of central Italy characterized by different level of disturbance. In each habitat-related bird community, we applied the recently published species-speci c score in hemeroby (a proxy of habitat-related disturbance; HSi) and hemerobiotic diversity (a proxy of generalism; H’Hi) to local species frequency, obtaining weighted values at community level (HStot and H’Htot). The relationship between HStot vs. H’Htot showed an increasing trend moving from reed beds through forests and mosa- ics to urban communities. Quadratic model (best t) evidenced a signi cant correlation between these variables and a tendency toward a hump-shaped curve, corroborating results already observed at species level (intermediate generalism hypothesis). The co-inertia analysis discriminated four groups of habitat-related communities, characterized by species with different levels of disturbance-sensitivity (expressed by HSi) and generalism (expressed by hemerobiotic diversity; H’Hi): (i) forest type-related, where mature wood communities were separated from a coppiced wood one; (ii) communities of moderately disturbed agri- cultural habitats; (iii) communities embedded in highly disturbed mosaics, and (iv) a group including either a highly disturbed urban habitat or a low disturbed wetland reed bed, with highly specialized species (respectively, synanthropic species and water-related species). Total scores in hemeroby and hemerobiotic diversity, expressing the composition in species with differ- ent disturbance preference and generalism, might act as good community-based indicators of degree of naturalness, especially for forest habitat types.