The beach thick-knee (Esacus magnirostris) belongs to the family of stone-curlews, dikkops and thick-knees, Burhinidae.
The beach thick-knee species are distributed in the Andaman and Nicobar Islands (India), Myanmar, Thailand, Malaysia, Singapore, Brunei, Indonesia, Philippines, Australia, New Guinea, Solomon Islands, Timor-Leste and Vanuatu. The IUCN has listed these thick-knee species as "Near Threatened". These thick-knees are monotypic species.
Beach thick-knee - Overview
- Scientific name: Esacus magnirostris
- Species author: (Vieillot, 1818)
- Synonyms/Protonym: Oedicnemus magnirostris Vieillot, 1818, Esacus neglectus, Burhinus giganteus, Burhinus magnirostris
- Family: Burhinidae › Charadriiformes › Aves › Chordata › Animalia
- Vernacular names: English: Beach thick-knee, Chinese: 澳洲石鸻, French: Oedicnème des récifs, German: Rifftriel, Spanish: Alcaraván piquigrueso australiano, Russian: Рифовая авдотка, Japanese: ハシブトオオイシチドリ, Indonesian: Wili-wili
- Other names: Beach Stone-curlew
- Distribution: Andaman and Nicobar Islands (India), Myanmar, Thailand, Malaysia, Singapore, Brunei, Indonesia, Philippines, Australia, New Guinea, Solomon Islands, Timor-Leste, Vanuatu
- Diet and feeding habits: crabs, crustaceans, small bivalve molluscs, marine worms, other invertebrates
- IUCN status listing: Near Threatened (NT)
Appearance, physical description and identification
The beach thick-knee (Esacus magnirostris) is a large wader, measuring 50 to 60 cm in length and weighing 870 to 1130 grams.The overall plumage of the thick-knee is shades brown. The upperparts like back, forehead, crown and nape are grayish brown. There is distinctive black and white pattern on the head, face, shoulders and secondary wings.
The grayish brown shoulder of the thick-knee is separated from the rest of the gray wing by a white border. The chin and throat are whitish. The lower throat and breast are pale grayish brown with fine darker streaks. The belly is whitish.
The adult beach thick-knee have large head and hunched profile. The massive black bill is slightly uplifted and has yellow patches at the base. The stout legs are pale grayish brown with thick ankles ("knees"). The eyes are large giving them a reptilian appearance. The irise are yellow.
The juvenile thick-knees are similar to the adults, but have duller plumage and the yellow patches on the bill are dull. The brown eye-stripe appears broken in juveniles. The beach thick-knee call is a repeated whistling “kee-wee..kee-wee” sound.
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| Birds of India - Image of Beach thick-knee - Esacus magnirostris by John Manger, CSIRO |
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| Indian birds - Picture of Beach thick-knee - Esacus magnirostris by Tony Morris |
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| Birds of India - Photo of Beach thick-knee - Esacus magnirostris by John Manger, CSIRO |
Origin, geographical range and distribution
The beach thick-knee species are distributed in the Andaman and Nicobar Islands (India), Myanmar, Thailand, Malaysia, Singapore, Brunei, Indonesia, Philippines, Australia, New Guinea, Solomon Islands, Timor-Leste and Vanuatu.The Important Bird and Biodiversity Areas (IBA) of these thick-knee species in Australia are, Tiwi Islands, Shoalwater Bay, Repulse Bay, Mackay, Proserpine River Sand Spit, Deadmans Creek New Beach, Ince Bay and Cooloola and Fraser Coast.
Ecosystem and habitat
These beach thick-knee species do not normally occur in forests. These species occur in altitudes from 0 to 100 meters.The natural ecosystems of these thick-knee species include intertidal rocky, sandy, pebble and shingle shoreline, mainland beach sand bars, tide pools, intertidal mudflats, brackish water lagoons, coastal marine lakes, exposed reefs, mangroves, sea cliffs, offshore islands and coastal marshes.
Diet and feeding behavior
The diet of these beach thick-knee species is mostly crabs. Crustaceans like crabs, small molluscs, marine worms and other marine invertebrates are their primary food.Though considered nocturnal, the beach thick-knee species are sometimes seen foraging by daylight. They roost during the high tide. During low tide, they move out to the exposed intertidal mudflats, sand flats and sandbanks to forage.
Reproduction and breeding habits
The breeding season of these beach thick-knee species is during September and February in Australia. The breeding season is from April to November in Indonesia. They are observed in pairs and probably these birds are monogamous.The beach thick-knee nesting sites include sandbanks, sandpits, islands in estuaries, coral ridges, mangroves and sandy areas surrounded by short grass. The nest is a bare scrape on the shore above the high-tide line.
The typical thick-knee clutch contains a single egg. The egg is exposed and highly vulnerable to predation. If the first egg is lost, a second maybe laid. Both the parents take care of the hatchling. The thick-knee chick is dependent on its parents for nearly 6 to 12 months.
Migration and movement patterns
The beach thick-knee species are non-migratory resident birds.Post breeding, the juvenile beach thick-knees may disperse and establish in new locations within the range. They may make local movements for feeding and breeding within their range.
Conservation and survival
The global population size of the beach thick-knee (Esacus magnirostris) is estimated to be around 6,000 individual birds (4,000 adults). The overall population trend of these thick-knee species is reported to be under decline.Throughout its range the thick-knee species is reported to be locally rare to uncommon. The generation length is 10.5 years. Its distribution size is about 29,800,000 sq.km.
Habitat loss, predation of adults, chicks and eggs by the introduced mammals and disturbances from human activities are the main threats that may endanger the survival of these thick-knee species.
IUCN and CITES status
The beach thick-knee (Esacus magnirostris) is approaching the thresholds for being Vulnerable, under the range size criterion, under the population trend criterion and also under the population size criterion.The IUCN (International Union for Conservation of Nature) has categorized and evaluated the thick-knee species and has listed it as "Near Threatened". The CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) status is ‘Not Evaluated’ for the beach thick-knee (Esacus magnirostris).
| Taxonomy and scientific classification of Esacus magnirostris | |
|---|---|
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Burhinidae |
| Subfamily: | - |
| Genus: | Esacus |
| Species: | E. magnirostris |
| Binomial name: | Esacus magnirostris |
| IUCN status listing: |
 Near Threatened |
1.Beach thick-knee picture source: https://commons.wikimedia.org/wiki/File:CSIRO_ScienceImage_10880_Beach_Stonecurlew.jpg (cropped)
Picture author: John Manger, CSIRO | License: CC BY 3.0
2.Picture source: https://www.flickr.com/photos/tonymorris/20565711415/ (cropped)
Picture author: Tony Morris | License: CC BY-NC 2.0 as on 6/18/17
3.Picture source: https://commons.wikimedia.org/wiki/File:CSIRO_ScienceImage_11070_Beach_Stonecurlew_Kurramine_Queensland.jpg (cropped)
Picture author: John Manger, CSIRO | License: CC BY 3.0
Current topic in Birds of India: Beach thick-knee - Esacus magnirostris.
