Winter and Early Spring Bird Communities in Grasslands, Shrubsteppe, and Juniper Woodlands in Central Oregon

We compared winter (December, January, and February) and early spring (March and April) bird communities among 4 successional stages that included grassland, shrubsteppe, juniper-shrubsteppe, and old-growth juniper woodland in central Oregon. Birds were surveyed monthly from December through April in 1998/1999 and 1999/2000 using the point count method to estimate relative abundance of birds (individuals · transect−1year−1). We used distance sampling to correct for potential bias in estimating abundance and density among successional stages. A total of 4513 birds (32 species) were detected. Relative abundance of total birds (all species combined) was similar in the juniper-shrubsteppe and old-growth woodland (48.7 and 48.9 individuals · transect−1, respectively) but 6 times greater than in the grassland and shrubsteppe (8.0 and 7.7 individuals · transect−1, respectively) during the 5-month period. Total density of birds was greater in old-growth juniper woodland and juniper-shrubsteppe than in gr...