Sula dactylatra


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Sula dactylatra
Species Authority: Lesson, 1831
Common Name(s):
English Masked Booby
Taxonomic Notes: Sula dactylatra (AOU 1998 + updates) and Sula tasmani (Christidis and Boles 1994) have been lumped as S. dactylatra following Christidis and Boles (2008).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ekstrom, J., Butchart, S., Calvert, R.
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Geographic Range [top]

Range Description: This species ranges widely in tropical waters, being found in every ocean on or off nearly every coast except the eastern Atlantic, northern Indian Ocean and the central-eastern Pacific (del Hoyo et al. 1992).
American Samoa (American Samoa); Anguilla; Antigua and Barbuda; Aruba; Australia; Bahamas; Barbados; Belize; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; Cape Verde; Cayman Islands; Chile; Christmas Island; Cocos (Keeling) Islands; Colombia; Comoros; Cook Islands; Costa Rica; Cuba; Curaçao; Dominica; Dominican Republic; Ecuador (Galápagos); Egypt; Eritrea; Fiji; French Polynesia; Guadeloupe; Guam; Guatemala; Haiti; India; Indonesia; Iran, Islamic Republic of; Jamaica; Japan; Kenya; Kiribati; Malaysia; Marshall Islands; Martinique; Mauritius; Mayotte; Mexico; Micronesia, Federated States of ; Montserrat; New Caledonia; New Zealand; Nicaragua; Norfolk Island; Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Puerto Rico; Réunion; Saint Helena, Ascension and Tristan da Cunha; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Seychelles; Sint Maarten (Dutch part); Solomon Islands; Somalia; Sri Lanka; Tanzania, United Republic of; Thailand; Tonga; Trinidad and Tobago; Turks and Caicos Islands; Tuvalu; United States (Hawaiian Is.); United States Minor Outlying Islands; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Yemen
Grenada; Maldives; Spain; United Arab Emirates
Present - origin uncertain:
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The global population size has not been quantified, but this species is described as 'fairly common' (Stotz et al. (1996).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This strictly marine species can normally be found over pelagic waters, preferring deeper waters than other boobies. It feeds on large species of shoaling fish, especially flying fish, but will also take large squid. Its breeding season depends on locality, forming small to medium-sized colonies of variable densities on rocky islands offshore. Nests are preferably built on cliff ledges, but a variety of other sites are used (del Hoyo et al. 1992).
Systems: Marine

Citation: BirdLife International 2012. Sula dactylatra. The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 01 April 2015.
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