Organic and integrated agriculture: the effects on bird communities in orchard farms in northern Italy

The objective of this study was to compare the effects of different farming methods on bird communities. In particular, the study surveyed the frequency and number of bird species, the number of individuals and bird diversity (Shannon index) found in organic (o, non use of synthetic pesticides), integrated (i, reduced use of pesticides on the basis of the economic threshold) and conventional (c, conventional use of pesticides) orchards. A simplified version of the mapping method was applied, from May to June 1998, to 60 fruit farms (15o, 19 i, 26c), over a total of 483 ha. Twenty-six bird species were observed (19o, 17i, 18c). Granivorous species were the most abundant and unaffected by pesticide management. Insectivorous species were less abundant in general, but more frequent on o and i farms (chi-square test, p<0.05). Bird diversity was greater in o and i farm management than in c (Tukey test, respectively, p = 0.001 and 0.004). There was a non-significant trend for bird density to be higher in o/i than c orchards (ANOVA, F _2.57 = 2.76, p = 0.07). The results confirm the positive effects of (o) and (i) agriculture on bird communities, including some species of special interest for nature conservation. These effects could be attributed mostly to the different pest management and secondarily to some aspects of environmental differentiation (type of orchard, type of farm, age and height of trees, and increased presence of hedgerows and woodlots). Surprisingly no correlation was observed between hedgerows and woodlots and bird diversity (Pearson test, R = 0.0019).