wibsa logo

Home
Species
Islands
Threats
Contribute
Contact

Roseate Tern Sterna dougallii dougallii


Roseate Tern from FAU
Photo: Sharyn Hood, Florida Fish and Wildlife Conservation Committee

At a glance

Highly specialized marine plunge diver

Adults desert breeding colonies and move when disturbed

Atlantic population Endangered

Little known about marine distribution outside the breeding season

Index

Identification:

There are a number of species of intermediate sized, black crowned, all white terns and they will prove difficult to identify to the inexperienced. Roseate terns are named for the pinkish cast to their breast, and this can be seen at close range on adult breeding season birds in flight. All black bill is shared with several other species of white terns. The Caribbean population have reddish orange bills with only the tips being black. When at rest the tails of breeding plumaged adults project past the wing tip. Tails of adults streamered. Juvenile and winter plumaged adults would be more difficult to identify. Most likely to be confused with Common and Arctic terns. Roseate Tern length 14 to 17 inches, 35-43 cm, Common Tern 12.25 to 15 inches. Arctic Tern 13-15 inches.  Of these three Roseate Tens have much paler plumage and heaver and darker bills.

Adults

Sexes alike but with seasonal variation in bill color. Feet and legs bright orange. During the breeding season the Caribbean population exhibits a reddish orange bill, and only the tip is black. In other populations except for the base the entire bill is black.

Juveniles

Juvenile and subsequent year birds distinguishable from adults. Backs grey with buffy cast and looked scaled. Bill and legs black.

Systematics

Differs from other medium sized similar appearing terns in downy chick characteristics and adult behavioral traits. Hybridizes with Common Tern and Arctic Terns, including F1 crosses and back-crosses. Five named subspecies but the nominate is the only one occurring in the Atlantic basin. 

Likely locations

Highly marine in distribution comes to land only to breed and roost at night. Seldom encountered except at and near breeding sites and at roosting areas on tropical wintering grounds.

Distribution

Coastal, but pelagic in migration. Occurs from northern South America and Gulf of Mexico to Canada. May be in mixed flocks with other terns during migration. Nesting disjunct, in western North Atlantic breeds in New England and southern Canada and another population occurs in Florida, the Bahamas Antilles and along northern South American coast and adjacent islands (Netherlands Antilles). Small numbers nest in Eastern North Atlantic, widespread in Old World tropics with additional subspecies occuring in South Africa, the Indian Ocean and the western tropical Pacific.

Country Low Estimate High Estimate
Bermuda 0 0
The Bahamas 1012 2379
Turks and Caicos 502 520
Cuba 41 68
Jamaica 7 29
Dominican Republic 1 20
Puerto Rico 1496 1685
US Virgin Islands 1088 4309
British Virgin Islands 18 700
Anguilla 210 220
St. Bartholomew 30 50
St. Kitts 7 16
Nevis 0 10
Guadeloupe 74 94
Dominica 0 0
Martinique 4 50
St. Lucia 66 75
St. Vincent & Grenadines 5 40
Granada 5 50
Trinidad and Tobago 333 423
Venezuela 3 40
Bonaire 0 0
Curacao 0 0
 Total 4902 10778

Biology

At sea

Migrates in flocks, probably with Common Terns. In West Indies region typically forages in small mixed species flocks with Sandwich Terns and Brown Noddies over shallow lagoons or just off shore, mainly within 2 km of colony. Often feeds over schools of predatory fish. Adapted for fast flight and relatively deep diving. Cannot hover as well as most terns. Fish specialist, in Puerto Rico main prey is small silversides and dwarf herring. Also feed on anchovies, sardines, and reef silversides.

At the nest

Adults can live for at least 26 years (probably longer as early banding studies had high loss of aluminum bands). Most individuals do not breed until they are 3-4 years old. Some West Indian colonies shift colonies annually, but retain strong site fidelity to specific groups of cays. Shifts or abandonment result from human disturbance, heavy predation, and reproductive failure due to patchy prey base. Adults return to colonies in late April and early May about three weeks prior to egg laying. Colonies mostly offshore on small rocky cays. Sites often barren or sparsely vegetated, ledges, slopes and cliffs, but also nest in vegetative cover of up to 90%. Nest simple shallow scrape, some nest material may be added later, but nest material less pronounced than Common Tern. Only one brood per season. Eggs brown with darker specks and streaks. Typical clutch size is 2, incubation period 23 days, fledging period 22-30 days.

Current Population 

Northern population 2,500 and 3,300 pairs; Caribbean population 4,000-6000 pairs; North Carolina 1-2 sporadic breeding attempts; British Isles (ca 800) pairs, and France (ca 120 pairs). Formerly nested in Bermuda but the nesting colony there has been abandoned for decades. Within the historical period as many as 10,000 pairs may have nested in just the West Indies. The total current Atlantic population is probably less than 8,000 pairs.

Conservation Status

The US Fish and Wildlife Service recognizes the population of this tern in northeast North America as Endangered and the disjunct Florida and Caribbean stock as Threatened (Federal Register: 42064). The nominate subspecies, endemic to the North Atlantic, is in sharp decline. The historical distribution and reliable population estimates within the West Indies region remain unavailable as early ornithologists often confused this species with Common Terns.

Conservation Needs

While egging has been eliminated at many sites it is still practiced to some extent in the West Indies. A major issue is the capture of some adult and large numbers of sub-adult birds on shore and at sea when these terns are on their wintering grounds (Guyana and w. Africa). Birds are netted at night with the use of jack-lighting, caught by hand when they land on fishing boats and also captured with baited lines. These may be the most important sources of mortality.

Pesticides and heavy metals are an issue. Puerto Rican birds had high concentrations of mercury, lead and cadmium in breast feathers. There is no indication that this is a by-catch species in pelagic fisheries but their diving behavior would appear to make them good candidates for by-catch mortality.

Loss of nesting habitat from development or other land use is an issue, and the species is sensitive to any disturbance early in the breeding cycle. More likely to desert nest after disturbance than other terns. Temporary dissertation leaved eggs and chicks vulnerable to predation. Posting colonies during nesting season and public education needed. Visits to cays with Roseate Tern colonies by tourist industry need to be regulated and tour leaders need to be educated as to the sensitive nature of the colonies.

Expanding Laughing Gull population, probably as a result of food supplementation from garbage and local fishing activities, detrimental to colonies as these gulls prey on unguarded chicks. Gull control in areas around nesting colonies should be considered.

Because of this tern’s movement between nesting sites it is difficult to obtain an accurate population assessment of the West Indian stock. Figures represent totals obtained from high counts at colonies over a many year period and are thus probably much higher than the total population. Within regions surveys need to be made of all known nesting sites within the same breeding season. Also individuals of the Northern Atlantic population are known to occur in breeding colonies. Because of these factors the assessment of the aggregate size of the West Indian population is most likely at the lower end of the range provided here.

Recovery plans have been formulated for the Caribbean population by US Fish and Wildlife Service as of 1993, but most nesting colonies and roosting site issues are outside the jurisdiction of the US government. Management suggestions consist of fencing of colonies, control of vegetation and predators (gulls and introduced mammals), providing shelters and other cover for chicks (nest boxes, tires, etc), sign posting, wardening, and enforcement.

Photos

Selected References:

Burger, J and M. Gochfeld. 1988. Nest-site selection by roseate terns in two tropical colonies on Culebra, Puerto Rico. Condor 90:843-851.

Gochfeld, M., J. Burger, and I. C. T. Nisbet. 1998. Roseate Tern (Sterna dougallii) in The Birds of North America, No. 370 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Lee, D. S. and J. F. Parnell. 1990. Endangered, threatened and rare fauna of North Carolina. Part III A Re-evaluation of the Birds. Occasional. Papers N.C. Biological Survey. 52 p.
.
Saliva, J. E. 2000. Conservation Priorities for Roseate Terns in the West Indies. Pages 87-95 in E. A. Schreiber and D. S. Lee (eds) Status and Conservation of West Indian Seabirds. Society of Caribbean Ornithology, Special Publication Number 1.225 pp.

Shealer, D. A. 1995. Comparative feeding ecology of Roseate and Sandwich Terns in Puerto Rico and its relation to breeding performance. Ph. D. dissertation, Rutgers University, New Brunswick, New Jersey. 228 pp.

Shealer, D. A. and J. Burger. 1992. Differential response of tropical roseate terns to aerial intruders throughout the nesting cycle. Condor 94: 712-719.

Shealer, D. A. and J. E. Saliva. 1992. Northeastern Roseate Terns seen at Puerto Rican colony during breeding season. Colonial Waterbirds 15: 152-154.

Nesbit, J. C. T. 1980. Status and trends of the Roseate Tern, Sterna dougallii in North America and the Caribbean. Unpublished Rep. U.S. Fish and Wildlife Service Office of Endangered Species.

Van Halewyn, R. and R. Norton. 1984.The status and conservation of seabirds in the Caribbean. Pages 169-222 in J. P. Croxall, P. G. Evans and R. W. Schreiber (eds). Status and Conservation of the World’s Seabirds. ICBP Tech. Publ., No. 2. 778 p.
Compiled by: Dave Lee and Will Mackin

West Indian Breeding Seabird Atlas by Will Mackin and David Lee is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License. Based on work at www.wicbirds.net. Permissions beyond the scope of this license may be available at www.wicbirds.net.

Suggested Citation: Lee, D. S., W. A. Mackin. 2009. Roseate Tern. West Indian Breeding Seabird Atlas <http://www.wicbirds.net/rost.html>. Last Updated: _____. Date accessed: ______.

WIBSA homepage
Creative Commons License Last updated:
June 26, 2009
Document made with KompoZer tortoisereserve.org