Avian guild structure and habitat associations in suburban bird communities

Breeding bird communities were compared in three suburbs: a 70-year-old area of larhe houses along streets shaded by mature trees (MT), primarily oaks (Quercus) and elms (Ulmus); a 15-year-old area built upon open agricultural land with young maple (Acer) street trees (YT); and a 15-year-old area on which houses were built in small clearings within a second-growth oak-pine (Quercus-Pinus) woodland (OP). Bird censuses each year for 5 years revealed that YT supported the lowest total avian density of the three suburbs; OP supported the greatest variety and total density of insectivores, and the lowest number of ground-gleaning omnivores; and MT supported the highest total avian density, comprised primarily of ground-foraging seed eaters and omnivores. Among nesting guilds, OP contained the fewest ground/herb nesters, and MT the most. Also, OP had the fewest shrub nesters, and MT the most. Tree cavity and twig nesters were significantly more numerous in OP, and tree branch nesters fewer in YT than in either OP or MT. Analyses of habitat structure revealed that shrub maturity is more important than numbers of shrubs, and that planted trees, no matter how mature or abundant, do not replace natural forest stands as habitat for most insectivorous species.