II. HABITAT & DISTRIBUTION
Regional Occurrence:
The range of E. rufescens extends from the coastal beaches of Texas to Florida in the Gulf of Mexico up to North Carolina on the Atlantic coast, throughout the Caribbean, and along both coasts of Mexico and Central America (Farrand 1983).
In Florida, E. rufescens is most common along the Gulf coast from Florida Bay north to Tampa Bay (Kale 1990). However, individuals have been documented as far north as St. Marks National Wildlife Refuge on the Gulf coast and Fernandina Beach on the east coast. The reddish egret is exclusively a coastal species, often associated with mangrove forests (Kale 1990).
Indian River Lagoon (IRL) Distribution:
Nesting populations have been documented in the IRL at Vero Beach and within the Merritt Island National Wildlife Refuge (Kale 1990), although individuals are likely found in other areas of the lagoon as well.
III. LIFE HISTORY & POPULATION
BIOLOGY
Age, Size, Lifespan:
The reddish egret is a medium-sized bird, reaching lengths of up to 82 cm.
Abundance:
Populations were estimated in the 1990s to number only 350 to 400 pairs throughout the state of Florida. The species is considered stable, although no further large-scale census attempts have been made in recent years (FWCC 2003) (see 'Threats and Conservation' below).
Reproduction:
Reddish egrets seem to prefer the red mangrove, Rhizophora mangle, as a nesting site, laying 2-5 bluish-green eggs on a platform constructed of twigs (Kale 1990). Breeding begins in December for populations in south Florida, and continues through June for birds in the northern parts of the range (Kale 1990; FWCC 2003). After eggs are laid, incubation is shared by both parents and lasts about 26 days. Juveniles are able to fly at around 45 days old and typically leave the nest after about 9 weeks (FWCC 2003).
Voice:
Adult reddish egrets are generally silent, but emit guttural croaks and chicken-like territorial clucks during the breeding season (Terres 1980).
IV. PHYSICAL TOLERANCES
Temperature & Salinity:
Information documenting the physical tolerances of the E. rufescens is scarce. However, its natural range suggests the species prefers and/or requires warm temperate to tropical climates near estuarine or marine waters for effective feeding and reproduction. Birds rarely visit freshwater sites (FWCC 2003).
V. COMMUNITY ECOLOGY
Trophic Mode:
Reddish egrets are active feeders on a variety of small fishes (e.g. FWCC 2003) and the only member of the heron family known to employ a foraging method termed 'canopy feeding' (Farrand 1983). By spreading their wings, hunting birds cast glare-reducing shadows as they step rapidly through shallow waters to catch their prey (Kale 1990).
Predators:
Little information is available concerning predators of the reddish egret. Due to their size and ability to retreat, it is unlikely that adult birds are regularly preyed upon. However, birds of prey, alligators or large mammals possibly consume eggs and hatchlings.
Associated Species:
Although there are no obligate associations documented between the reddish egret and other species, E. rufescens is commonly found alongside other organisms from the seagrass beds, mangrove forests, tidal flats and other ecosystems in which it resides. For more extensive information on these environments and their associated species found in the IRL, please visit the Habitats of the IRL page.
VI. SPECIAL STATUS
Special Status:
Species of Special Concern, Criteria #1 and #4 (SSC 1, 4)
The reddish egret is listed as a species of special concern based on its vulnerability to habitat modification and human disturbances that may threaten the species in the absence of effective management and conservation strategies, as well as its delayed recovery from past population depletion (FWCC 2009).
Threats & Conservation:
The reddish egret is considered to be Florida’s least common heron, with decreased population sizes presumably due to plume hunting during the 19th century, from which the species never fully recovered (Powell et al. 1989; Kale 1990) (see 'Abundance' above).
VII. LITERATURE CITED & OTHER USEFUL REFERENCES
Farrand Jr., J (Ed.). 1983. The Audubon Society Master Guide to Birding Volume 1: Loons to Sandpipers. Alfred A. Knopf. New York. USA. 447 pp.
FNAI. 2001. Field Guide to the Rare Animals of Florida. Florida Natural Areas Inventory.
FWCC. 2003. Florida’s Breeding Bird Atlas: A Collaborative Study of Florida’s Birdlife. Florida Fish and Wildlife Conservation Commission. http://www.myfwc.com/bba/ (Date accessed 07/01/2010).
FWCC. 2009. Florida’s endangered species, threatened species, and species of special concern. Florida Fish and Wildlife Conservation Commission. Online at http://myfwc.com/WILDLIFEHABITATS/imperiledSpp_index.htm (Date accessed 08/07/2010).
Kale II, HW & DS Maehr. 1990. Florida’s Birds. Pineapple Press. Sarasota, FL. USA. 288 pp.
Powell, GVN, Bjork, RD, Ogden, JC, Paul, RT, Powell, AH & WB Robertson, Jr. 1989. Population trends in some Florida Bay wading birds. Wilson Bull. 101: 436-457.
Terres, JK. 1980. The Audubon Society Encyclopedia of North American Birds. Alfred A. Knopf. New York. USA. 1109 pp.
Report by: LH Sweat,
Smithsonian Marine Station at Fort Pierce
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