Bird Usage of Hybrid Poplar Plantations Annual Progress Report 1996

Abstract

We continued to collect baseline data on the large plantations that have been established in the Alexandria area. Three sites have been surveyed for four years, six sites for three years, and four sites f.or two years. We observed a linear growth in mean numbers of individuals and species on plantations as they have aged from one to six years. Species diversity has plateaued after five years on two sites. Plantations that had partial tree failure in previous years had greater species diversity. This was expected because these sites have two or three ages of trees present on the site and were more heterogeneous in the bird habitat they provided. Species turnover rates were 57% for plantations that aged from one to two years and were 53% for plantations that aged from two to three years. The largest proportion of bird individuals in plantations in the first six years were short-distance migrants. Numbers of individuals that migrate long-distances to Central and South America increased slightly as the plantations aged. Very few permanent resident birds were found in plantations at any age. Most individuals observed in the plantations at all ages were ground feeding birds associated with open field and pasture habitats. Very few foliage gleaners individuals and those associated with forested habitats were observed in the plantations at any age. Numbers of shrub birds and those that eat seeds increased as the plantations have grown. Studies were again (repeated from 1995) conducted on predation rates of artificial bird nest~ to test the hypothesis that predation rates in forests and grasslands adjacent to plantations are not affected by distance to the edge of the plantation. Data collected on predation rates this past summer support the alternative hypothesis that predation rates are independent of habitat type and distance from edge of plantation. We found that predations rates were site specific and were likely affected by local predator populations. These results support conclusions made from similar studies collected in 1995. The geographic information system (GIS) that included land cover types within a 2-3 mile radius of each plantation in the Alexandria area (for details see small mammal report) was completed. Canonical correspondence analyses (CANOCO) on the plantations established after or during 1994 indicated that the landscape surrounding many plantations was similar and was dominated by cropland. Exceptions to this were the Kreyer and Nelson sites which had .more water, woodland, and pasture (Kreyer) and wet and dry wildland (Nelson) in the surrounding landscape. Bird species such as the Sedge Wren, Mallard, Common Yellowthroat, Ring-necked Pheasant, Blue-winged Teal found within the Nelson site relected the presence of the adjacent wet and dry wildland habitat. The Chipping Sparrow, Eastern Bluebird, Grasshopper Sparrow and Vesper Sparrow found in the Kreyer site reflected the composition of the surrounding forest and pasture habitat.