Use of successional habitat and fruit resources by songbirds during autumnmigration in central New Jersey

We evaluated the effects of plant succession on habitat use and fruit resou rce availability for autumn migratory and resident songbirds in 43 ha of ab andoned farm fields in central New Jersey. Using fixed net sites, standardi zed effort, and simultaneous sampling across habitat types, we mist-netted birds to compare habitat use and found that (1) use of three shrub-tree inv asion interfaces declined as fruit-bearing shrubs were overgrown by trees, while use of three open shrublands changed little over the same period; (2) use of two pairs of contrasting successional habitats, shrubland and young woodland, was higher in the shrubland with abundant, highly nutritional fr uits than in young woodland with sparse fruit; and (3) use of three shrubla nds at similar successional stages but with different fruit availability di ffered by bird taxonomic family and migratory strategy. Data on species com position and relative abundance of fruit-bearing shrubs and fruit consumpti on by birds (assessed by regurgitated and defecated matter) were used to el ucidate avian patterns of habitat use. The relative abundance of fruit-bear ing species may be more important than habitat structure in determining hab itat use by birds. Shrubland dominated by panicled dogwood (Cornus racemosa ) was favored over shrubland dominated by red cedar (Juniperus virginianum) or multiflora rose (Rosa multiflora). Favored vines were Japanese honeysuc kle (Lonicera japonica), Virginia creeper (Parthenocissus quinquefolia), po ison ivy (Toxicodendron randicans), and grape (Vitis spp.).