Bird community structure and dynamics during spring migration in selected habitats of northern Italy

Abstract

Bird community structure and dynamics were studied in seven habitats of northern Italy during three periods. Respectively 87 and 70 species were detected in 1984 and 1985 (a total of 98 species for 1984 + 1985). Of these, 45% belonged to permanent resident species. This category was dominant in abandoned mountain farmland, shrublands, young wood and abandoned chestnut orchard.

The tree cover was negatively correlated with bird diversity. The permanent resident and transient migrant species had the highest interseason turnover. Abandoned chestnut orchard showed the highest value of specific dominance (322). The species with the widest habitat breadth (> 0.80) were: blackcap (Sylvia atricapilla), blackbird (Turdus merula), great tit (Parus major) and greenfinch (Carduelis choris).

Based on the relative abundance of single species abandoned chestnut orchards, shrubland and young wood were the habitats with the most similar bird community. Seven species had an acoustic repertoire breadth > 0.60. The permanent residents and summer migrants were the least acoustically varied species. Transient migrant birds were attracted to open fields and shrubland habitats. Woodland habitats had a more evenly distributed bird assemblage.

The availability and concentration of food in patchy habitats were probably most responsible for habitat choice during the period studied. Permanent residents and winter migrants showed the broadest habitat preferences. The spatial heterogeneity of birds decreased during spring according to a more diffuse distribution of resources.

The interpretation of the specific acoustic repertoire could be helpful in distinguishing intraspecific populations.

Key words:

• Bird community
• Community structure
• Community dynamics
• Spring migration
• Italian bird communities