Monday, March 27

Lesser crested tern

   ›      ›   Lesser crested tern - Thalasseus bengalensis

The lesser crested tern (Thalasseus bengalensis) belongs to the family of terns, Sternidae.

These tern species are distributed in coastal regions of Indian subcontinent, northwest and east African coast, Madagascar, coasts around Bay of Bengal, southeast Asian coasts, northern Australian coast and Papua New Guinea.

Genetic data suggests that lesser crested tern is closely related to royal tern (Thalasseus maximus). There are three recognized subspecies of lesser crested tern.

Overview & Quick Facts Description & Identification
Pictures of Lesser Crested Tern Distribution & Range
Ecosystem & Habitat Diet & Feeding Behavior
Breeding Habits Migration & Movement Patterns
Conservation & Survival IUCN Status
Taxonomy & Classification Bird World

Lesser crested tern - Overview

  • Scientific name: Thalasseus bengalensis
  • Species author: (Lesson, 1831)
  • Synonyms/Protonym: Sterna bengalensis Lesson, 1831
  • Family: Sternidae › Charadriiformes › Aves › Chordata › Animalia
  • Vernacular names: English: Lesser crested tern, Chinese: 小凤头燕鸥, French: Sterne voyageuse, German: Rüppellseeschwalbe, Spanish: Charrán bengalí, Russian: Бенгальская крачка, Japanese: ベンガルアジサシ, Malay: Burung Camar Berjambul Kecil
  • Other names: Little crested Tern
  • Distribution: northeast African coast and inshore islands, East coast of Africa, Madagascar, coast of Indian subcontinent, coastal regions of Bay of Bengal, southeast Asian coasts, northern Australian coast, Papua New Guinea
  • Diet and feeding habits: fish and shrimps
  • IUCN status listing: Least Concern (LC)
The lesser crested tern (Thalasseus bengalensis) is considered closely related to royal tern (Thalasseus maximus), elegant tern (Thalasseus elegans), Sandwich tern (Thalasseus sandvicensis) and Chinese crested tern (Thalasseus bernsteini).

The three recognized subspecies of lesser crested tern are: Thalasseus bengalensis bengalensis (Lesson, 1831), Thalasseus bengalensis emigratus (Neumann, 1934) and Thalasseus bengalensis torresii Gould, 1843.

Appearance, physical description and identification

The lesser crested tern (Thalasseus bengalensis) is a medium-sized bird measuring 35 to 45 cm in length and weighing 180 to 240 grams. The wingspan is 90 to 105 cm.

The overall plumage of the lesser crested tern is a uniform gray on the upperparts and white on the underparts. Its characteristic gray rump helps in differentiating from similar looking terns. The breeding tern adult has a black cap and black crest.

The upperwings and central tail feathers are grey. The underwings are white with grayish trailing edge. The webbed legs are black. The bill is long and yellowish orange in color. Their call is a characteristic loud grating "kear-ik..kear-ik" sound.
Indian bird - Picture of Lesser crested tern - Thalasseus bengalensis adult
Birds of India - Image of Lesser crested tern - Thalasseus bengalensis by shrikant rao

Birds of India - Photo of Lesser crested tern - Thalasseus bengalensis juvenile
Indian birds - Picture of Lesser crested tern - Thalasseus bengalensis by shrikant rao

Indian birds - Image of Lesser crested tern - Thalasseus bengalensis in flight
Birds of India - Photo of Lesser crested tern - Thalasseus bengalensis by shrikant rao

Origin, geographical range and distribution

The lesser crested tern species are distributed in the coastal regions of Indian subcontinent, northwest and east African coast, Madagascar, coasts around Bay of Bengal, southeast Asian coasts, northern Australian coast and Papua New Guinea.

The lesser crested tern nominate subspecies T. b. bengalensis are distributed in the coastal regions and nearby islands in Red Sea, Persian Gulf and Indian Ocean. These subspecies winter in South Africa, Madagascar and Sri Lanka.

The lesser crested tern subspecies T. b. emigratus are distributed in Libyan coast. The subspecies T. b. torresii is distributed in several Indonesian islands, New Guinea and North Australia.

The Important Bird and Biodiversity Areas (IBA) of lesser crested tern in Madagascar are, Wetlands of the Tsiribihina delta and upper Tsiribihina river, Tambohorano Wetland NPA, Ambavanankarana wetland, Baly Bay National Park, Cape Anorontany Archipelago NPA, Mahavavy - Kinkony wetlands NPA and Sahamalaza - Radama Islands National Marine Park.

The Important Bird and Biodiversity Areas (IBA) of lesser crested tern in Libya are Geziret Garah and Geziret al Elba - Ayn al Ghazalah Bay. The IBA in Kenya are Sabaki River Mouth and Tana River Delta. The IBA in Iran are Kharku Wildlife Refuge and Nakhilu, Morghu and Ummal Karam islands.

The Important Bird and Biodiversity Areas (IBA) of lesser crested tern in Saudi Arabia are Abu Ali, Gulf coral islands and Gulf of Salwah. The IBA in Tanzania are Dar es Salaam coast, Rufiji Delta and Na Muang Krabi. The IBA of these terns in Sudan are Suakin archipelago, Mukawwar island and Dunganab bay.

The Important Bird and Biodiversity Areas (IBA) of lesser crested tern in Australia are Brook Islands, Sudbury Reef, Cape York to Cape Grenville Islands, Stapleton Island, Islands North of Port Stewart, South Barnard Islands and Michaelmas Cay. The IBA in Egypt is Hurghada archipelago.

Ecosystem and habitat

These lesser crested tern species do not normally occur in forest. These species occur in altitudes from 0 to 100 meters.

These lesser crested tern species inhabit natural ecosystems like offshore islands, intertidal mud flats, rocky, pebbly, shingle and sandy shoreline, beaches, tide pools, lagoons, estuaries, coral reefs and shallow seas with macroalgae like kelp and seagrass.

Diet and feeding behavior

The diet of these lesser crested tern species is mostly fish. Pelagic fish and shrimp are their primary food. They are gregarious while foraging. Foraging flocks of single or mixed-species comprising up to 400 individual birds can be observed. They feed by plunge-diving for fish.

Reproduction and breeding habits

The breeding season of the lesser crested tern is from September to December in Australia. The breeding season is in May and June in Persian Gulf. The laying season is in July and August in Libya. The breeding season in Somalia is in August.

These lesser crested tern species are colonial breeders, breedig in dense colonies of even up to 20,000 pairs. The nesting sites are located on inshore islands, low-lying offshore islands, coral flats, coral islands, sandbanks, inter-reef substrates and flat sandy beaches.

The lesser crested tern nest is a shallow scrape surrounded by vegetation. One to three spotted eggs are laid. The closeness of nests provides them protection from predators.

Migration and movement patterns

The lesser crested tern species are partially migratory birds.

There is inadequate information available about the movement patterns of these lesser crested tern species. Some northern populations in Africa and Middle East appear to move southwards for wintering at the end of the breeding season. The populations in Australia appear to be sedentary.

Post breeding, the tern juveniles may disperse and establish in new locations within the range. They sometimes may make local movements for feeding and breeding within their range.

Conservation and survival

The global population size of the lesser crested tern (Thalasseus bengalensis) has not been quantified. The overall population trend of these tern species is considered to be stable. Throughout its range it is reported to be common to uncommon. The generation length is 11 years. Their distribution size is about 41,500,000 sq.km.

The lesser crested tern (Thalasseus bengalensis) does not approach the thresholds for being Vulnerable, either under the range size criterion, or under the population trend criterion or under the population size criterion. Oil exploration activity and oil spills are the main threats that may endanger the survival of these tern species.

IUCN and CITES status

The IUCN (International Union for Conservation of Nature) has categorized and evaluated the tern species and has listed it as of "Least Concern". CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) status is ‘Not Evaluated’ for the lesser crested tern (Thalasseus bengalensis).
Taxonomy and scientific classification of Thalasseus bengalensis
Kingdom:Animalia
Phylum:Chordata
Class:Aves
Order:Charadriiformes
Family:Sternidae
Subfamily:-
Genus:Thalasseus
Species:T. bengalensis
Binomial name:Thalasseus bengalensis
IUCN status listing:
Least Concern
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1.Image source: https://www.flickr.com/photos/9494793@N06/25151582519/in/photostream/ (cropped)
Image author: shrikant rao | License: CC BY 2.0 as on 3/27/17
2.Image source: https://www.flickr.com/photos/9494793@N06/24356461733/in/photostream/ (cropped)
Image author: shrikant rao | License: CC BY 2.0 as on 3/27/17
3.Image source: https://www.flickr.com/photos/9494793@N06/25492997716/ (cropped)
Image author: shrikant rao | License: CC BY 2.0 as on 3/27/17
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