Determinants of Great Blue Heron Colony Distribution in Coastal Maine

Abstract

AI•STRACT.--The distribution of nesting Great Blue Herons (Ardea herodias) in coastal Mainewas studied by examining the relationship between colony size and availability of food supplies near colonies, the selection of nesting habitat, and the spacing of colonies. Nineteen colonies (size range 4-252 nests) were located, all on marine islands. The number of nests in a colony was correlated positively (r = 0.82) with the area of tidal and inland wetlands within a 20-km radius of a colony. Nest and colony characteristics were highly variable, and suitable nesting habitat did not seem to limit colony size or distribution. The degree of forestation, presence of hardwoods, and distance of an island from towns and other islands with colonies were apparently important factors in selection of nesting islands. Colonies were uniformly distributed along the coast at intervals of about 16 km. We present a model for the observed dispersion of heron nests based on the conclusion that food competition between members of the same colony probably limits the size of colonies, whereas food competition between members of adjacent colonies may determine colony distribution. Re-

Evaluation of habitat quality for selected wildlife species associated with island back channels

“…On the Ohio River, this condition is met most readily on the islands. Herons prefer isolation particularly during nesting [17,32,33]. Indeed, all active nests observed within our study area occurred on islands.…”

Movement Patterns of Adult Laughing GullsLarus atricillaDuring the Nesting Season

“…The locations of Great Blue Heron Ardea herodias colonies in Maine and British Columbia (Gibbs et al 1987, Gibbs 1991, Butler 1995 are related to their position relative to good foraging habitats. Therefore, the availability of energetically profitable locations for colonies is not necessarily limited by the number of suitable nesting sites, but rather by the spatial relationship of their feeding areas, inland wetlands, to suitable colony sites (Gibbs 1991).…”

Importance of Proximity to Foraging Areas for the Pacific Great Blue Heron (Ardea herodias fannini) Nesting in a Developed Landscape

“…The degree of forestation, presence of hardwoods, and distance of an island from towns and other islands with colonies were apparently important factors in selection of nesting islands by Great Blue Heron in Maine (Gibbs et al 1987). In addition, Gibbs (1991) found that Great Blue Heron colonies in Maine were closer to local concentrations of foraging than expected by chance.…”

“…The number of nests has also been positively related to the size of nearby foraging areas in British Columbia (Butler 1991a), Oregon (Werschkul et al 1977;Bayer and McMahon 1981), and Maine (Gibbs 1991;Gibbs et al 1987). In Maine, Gibbs (1991) concluded that the spatial arrangement of wetlands upon the landscape of inland Maine limited the availability of nesting sites with efficient access to heron foraging areas, and favoured clumped nesting patterns.…”