Current Distribution Rangewide

Global distribution characterized by disjunct colonies occurring from the Pacific side of Northwest Mexico to the Caribbean [1]. Found on Pacific coasts in Mexico, along both coasts of Baja California, on Atlantic coasts from south Florida Alabama, Louisiana, Texas, and into Mexico. Also along coast of Yucatan Peninsula, Mexico, and north Belize, and probably Jamaica and Hispaniola, coastal Columbia and islands south of the Caribbean during the breeding season [2]. Still found in coastal areas of breeding range during the non-breeding season [2;3]. San Diego marks the northern limit of the usual range along the Pacific coast [4].

Known Populations in San Diego County

Known to occur in Los Penasquitos Lagoon, San Diego River Estuary, San Elijo Lagoon, Batiquitos Lagoon, and the Santa Margarita Estuary [4].

List Status

None.

Habitat Affinities

Strictly coastal [2]. Found in bays/sounds, herbaceous wetlands, lagoons, river mouths/tidal rivers, scrub-shrub wetlands, and tidal flats/shores [3].

Taxonomy and Genetics

Three subspecies are currently recognized: E. r. rufescens, E. r. disckeyi, and E. r. colorata. These subspecies have not been evaluated using molecular tools and appear to be weakly differentiated morphologically [2). Research indicates three evolutionarily distinct population units that support the subspecies E.r. dickeyi in Baja California and propose a new unique population within E. r. rufescens occurring in Great Inagua, Bahamas [1].

Seasonal Activity

Weakly migratory among northern portions of breeding range [5, cited in 2]. Strong southward movement from September to November [2]. Seen in San Diego County every month of the year, with its frequency peaking in October and November with the dipersal of immatures [4]. Both adults and juveniles are crepuscular and dirurnal [3].

Life History/Reproduction

Generally solitary, though often near other foraging herons [6 cited in 3, 4]. Nesting occurs primarily from March through June. Clutch size usually 3 to 4 eggs [2;7]. Estimated incubation period of 25 to 26 days [7]. Colonial breeders [3]. Young are semiprecocial [2]. Although known to live at least 11 years, 3 months, juvenile/adult survivorship is unknown [8, cited in 3].

Diet and Foraging

Forages in shallow coastal flats, ponds and lagoons including wind-tidal flats and alluvial overwash zones of barrier islands, open banks and ponds inside keys, intertidal flats, salterns, occasionally open beaches and reefs and in hypersaline flats and solar salt ponds [9]. Primarily feeds on small fish, crustaceans, and insects [2;8, cited in 3]. Possess the most active feeding methods, which include openwing, canopy feeding, foot-stirring, hovering-stirring, and stand and wait [2;10].

Dispersal

Year-round resident in some portions of its range, predominantly in the Southeastern United States [1] but migratory elsewhere. Postnesting dispersal occurs soon after immature independence [2]. Young may leave nests at about 4 weeks but incapable of sustained flight until 6 to 7 weeks of age [11]. Most movement occurs along coastlines [2].

Threats

Primarily threatened by habitat shifting and alteration from sea-level rise and subsidence, coastal engineering and development, and urban development [9].

Literature Sources