Bird diversity in agroforestry landscapes: a case study in Uruguay

In Uruguay extensive forestry is expanding continuously and it currently covers 5.6% of our territory. One of the biological groups which are considered to be negatively affected by this activity are grassland birds, and little is known about the bird assemblages which make use of these habitat types. In this study the following questions are expected to be answered: How do the ecoregion (regional factor) and the habitat type (local factor) contribute to the local variation of bird diversity in agro-forest habitats? Does forestry displace local grassland bird species while favoring forest species? During 2015-2016, 160 point count bird surveys were conducted for each habitat type: native forest, grassland, artificial forest. These were distributed in the same proportion along four of the country’s ecoregions, as well as in summer and winter seasons. Six alpha diversity and species composition variables were assessed by means of ANOVA and ANOSIM respectively, taking into consideration these three factors: ecoregion, season and local habitat type. Local habitat type was the main determinant of the variation in species diversity and composition (0.43<r2<0.79, p0.12, p<0.001). Furthermore, forestry caused an almost total displacement of the grassland community and the species found in this habitat type are, in their majority, generalist species with smaller populations than those found in native forests. Notwithstanding this, some forest specialist species were recorded and nesting events were confirmed, which shows the new habitat type is being used to the advantage of some species.