Breeding bird counts were conducted in 12 mesic hardwood hammock islands in north central Florida during April and May 1978. The number of species observed to defend territories in the habitat islands was a direct function of island area. The form of the species-area curve is sensitive to the criterion used to define a “breeding” species. If presence on 3 of 4 counts is required before a recorded species is considered to be a breeding species, then small islands are shown to support many fewer species and the slope of the species area curve is increased by 25 %. The number of breeding bird species appears to double for every 7.25-fold increase in area. Small, disjunct habitat islands (≤30 ha) do not support a large proportion of the bird species characteristic of north Florida hardwood forests. The 12 islands studied supported only 64% of the species that breed in hardwood forests and only 46% of the 13 species that are restricted to this forest type. The species that do not reproduce in the small islands (area-sensitive species) deserve greater attention in nongame monitoring and conservation programs.