We examined territory selection of Red-winged Blackbirds (Agelaius phoeniceus) in experimental treatments with varied groundcovers and densities of planted and naturally occurring oaks (Quercus spp.) used by blackbirds for perching. We also compared vegetation parameters between blackbird territories and unused (i.e., unoccupied by Red-winged Blackbirds) areas. Although perch densities were greater in blackbird territories in unplanted controls and oak-planted treatments without redtop grass (Agrostis gigantea) than they were in unused areas, the low densities of perches in territories planted with redtop grass indicate that perch density is not limiting above some lower threshold. Territories, particularly in treatments with no redtop, tended to have greater mean grass cover and taller grass heights than unused areas. Our results are consistent with other studies in finding that Red-winged Blackbirds prefer areas having tall vegetation and dense grass.
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Vol. 118 • No. 3