Reddish Egret Research Articles

Habitat Use by Wading Birds in a Subtropical Estuary: Implications of Hydrography

Abstract The dynamics of foraging habitat use by long-legged wading birds was analyzed with respect to water-level fluctuation patterns in Florida Bay. Wading-bird presence at four sites situated to sample the heterogeneity of the bay was quantified by repeated surveys collected throughout the day and year. Models for habitat availability were generated using water-level data collected from continuous recorders, staff guages, and habitat profile maps. These models were tested against the survey data. Roseate Spoonbills (Ajaia ajaja) foraged on the study areas primarily at night. Great Blue Herons (Ardea herodias) fed both day and night, but primarily at night where the tidal range was small. Great Egrets (Casmerodius albus), Snowy (Egretta thula) and Reddish (E. rufescens) egrets, Little Blue (E. caerulea) and Tricolored (E. tricolor) herons, and White Ibis (Eudocimus albus) fed during daylight. Where tidal range was small (<5 cm) diurnal species fed throughout the day. Florida Bay has a pronounced annual water-level cycle that causes monthly mean water levels to vary by as much as 30 cm between October (high) and May (low). Models derived from hydrology data predicted that this seasonal variation in water level would have a major impact on habitat availability, particularly where tidal flux was small. The predictions were supported by survey data. At sites with minor tides, most wading-bird species had a cycle in seasonal abundance that correlated with seasonal changes in water level; only the tallest species, Ardea herodias, was uniformly present throughout the year. The large daily range in tide (x̄ = 80 cm) afforded year-round access to foraging habitat, and these abundance patterns did not exist. The seasonal variability in habitat availability has major management implications because the maintenance of stable wading-bird populations depends on the availability of alternative foraging sites when water levels are high. Historically, these sites have tended to be targeted for human development.

Parasites and Diseases of Reddish Egrets (Egretta rufescens) from Texas and Florida

Parasites and Diseases of Reddish Egrets (Egretta rufescens) from Texas and Florida

History and Current Status of Reddish Egrets in the United States

History and Current Status of Reddish Egrets in the United States

Discovery of a Golden Eagle Nest on the Alaska Peninsula

Feeding relationships between Snowy Egrets (Egretta thula) and Red-breasted Mergansers (Mergus serrator), often involving other waterbirds as well, have been the subject of published comment on several recent occasions. Christman (Condor 59:343, 1957) described an occurrence in San Diego County, California. Parks and Bressler (Auk 80:198, 1963) and Emlen and Ambrose (Auk 87:164, 1970) were concerned with similar feeding movements in Florida, the former also citing an instance involving Hooded Mergansers (Lophodytes cucullatus). Another, but more complex, example was observed early in the morning on 2 December 1972 at Bahia de la Concepci6n (ca. 26038' N, 111050' W) on the Gulf of California in central Baja California. The principal element consisted of about 40 Red-breasted Mergansers which were swimming together, with their heads often below the water, parallel to the rocky shoreline and ranging from 10 to 30 ft from the shore. Moving along the shore abreast of the ducks were 7 Snowy Egrets, a Reddish Egret (Dichromanassa rufescens), 18 Heermann's Gulls (Larus heermanni), and 3 Ring-billed Gulls (Larus delawarensis). This assemblage was gradually augmented by another Reddish Egret, two Brown Pelicans (Pelecanus occidentalis) and a Double-crested Cormorant (Phalacrocorax auritus). The pelicans and cormorant stayed on the open-water side of the ducks. When the mergansers found fish and commenced diving, the whole scene became one of frenzied activity. As the fish sought to escape, some fled toward the shore, and the herons moved into shallow water and darted about, snatching them up. The pelicans and cormorant fed on fish which moved toward deeper water. The Heermann's Gulls showed an interest in the mergansers but did not obtain any food from them; they did successfully harass the pelicans, and both they and the Ring-billed Gulls robbed the Snowy Egrets. Both species of gulls also waded in to get food from the shallow water, perhaps bits of fish. It was not possible to examine any of the fish but they appeared to be small, about 3 inches in length. After a few minutes, the school of fish was dissipated or moved to deeper water. The procession then moved on. Three such scenes of activity involving the same group of birds were observed in the 40 min of observation.

Symbiotic Relationships within a Mixed Waterfowl Assembly

Feeding relationships between Snowy Egrets (Egretta thula) and Red-breasted Mergansers (Mergus serrator), often involving other waterbirds as well, have been the subject of published comment on several recent occasions. Christman (Condor 59:343, 1957) described an occurrence in San Diego County, California. Parks and Bressler (Auk 80:198, 1963) and Emlen and Ambrose (Auk 87:164, 1970) were concerned with similar feeding movements in Florida, the former also citing an instance involving Hooded Mergansers (Lophodytes cucullatus). Another, but more complex, example was observed early in the morning on 2 December 1972 at Bahia de la Concepci6n (ca. 26038' N, 111050' W) on the Gulf of California in central Baja California. The principal element consisted of about 40 Red-breasted Mergansers which were swimming together, with their heads often below the water, parallel to the rocky shoreline and ranging from 10 to 30 ft from the shore. Moving along the shore abreast of the ducks were 7 Snowy Egrets, a Reddish Egret (Dichromanassa rufescens), 18 Heermann's Gulls (Larus heermanni), and 3 Ring-billed Gulls (Larus delawarensis). This assemblage was gradually augmented by another Reddish Egret, two Brown Pelicans (Pelecanus occidentalis) and a Double-crested Cormorant (Phalacrocorax auritus). The pelicans and cormorant stayed on the open-water side of the ducks. When the mergansers found fish and commenced diving, the whole scene became one of frenzied activity. As the fish sought to escape, some fled toward the shore, and the herons moved into shallow water and darted about, snatching them up. The pelicans and cormorant fed on fish which moved toward deeper water. The Heermann's Gulls showed an interest in the mergansers but did not obtain any food from them; they did successfully harass the pelicans, and both they and the Ring-billed Gulls robbed the Snowy Egrets. Both species of gulls also waded in to get food from the shallow water, perhaps bits of fish. It was not possible to examine any of the fish but they appeared to be small, about 3 inches in length. After a few minutes, the school of fish was dissipated or moved to deeper water. The procession then moved on. Three such scenes of activity involving the same group of birds were observed in the 40 min of observation.

First Specimen of Reddish Egret from British Honduras

First Specimen of Reddish Egret from British Honduras

Northern Breeding Record for Reddish Egret

Northern Breeding Record for Reddish Egret

Reddish Egret in Central Texas

Reddish Egret in Central Texas

Recent Northward Penetration of the Reddish Egret in Florida

Recent Northward Penetration of the Reddish Egret in Florida

Reddish Egret Nesting near Tavernier, Florida

Reddish Egret Nesting near Tavernier, Florida

The Reddish Egrets of Cameron County, Texas

The Reddish Egrets of Cameron County, Texas