Oystercatcher

The oystercatchers are a group of waders forming the family Haematopodidae, which has a single genus, Haematopus. They are found on coasts worldwide apart from the polar regions and some tropical regions of Africa and South East Asia. The exceptions to this are the Eurasian oystercatcher, the South Island oystercatcher, and the Magellanic oystercatcher, which also breed inland, far inland in some cases. In the past there has been a great deal of confusion as to the species limits, with discrete populations of all black oystercatchers being afforded specific status but pied oystercatchers being considered one single species.[1]

Oystercatchers Temporal range: Middle Miocene–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Pied oystercatcher (Haematopus longirostris)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Charadriiformes
Suborder:	Charadrii
Family:	Haematopodidae Bonaparte, 1838
Genus:	Haematopus Linnaeus, 1758
Species
See text

American oystercatcher

Juvenile

The name oystercatcher was coined by Mark Catesby in 1731 as a common name for the North American species H. palliatus, described as eating oysters.[2] Yarrell in 1843 established this as the preferred term, replacing the older name sea pie[2][3] or sea-pie.[4] The genus name Haematopus comes from the Greek haima αἳμα blood, pous πούς foot.[5]

Description

The different species of oystercatcher show little variation in shape or appearance. They range from 39–50 centimetres (15 ¹⁄₂–19 ¹⁄₂ inches) in length and 72–91 cm (28 ¹⁄₂–36 in) in wingspan. The Eurasian oystercatcher is the lightest on average, at 526 grams (1 pound 2 ¹⁄₂ ounces), while the sooty oystercatcher is the heaviest, at 819 g (1 lb 13 oz).[6] The plumage of all species is either all-black, or black (or dark brown) on top and white underneath. The variable oystercatcher is slightly exceptional in being either all-black or pied. They are large, obvious, and noisy plover-like birds, with massive long orange or red bills used for smashing or prying open molluscs. The bill shape varies between species, according to the diet. Those birds with blade-like bill tips pry open or smash mollusc shells, and those with pointed bill tips tend to probe for annelid worms. They show sexual dimorphism, with females being longer-billed and heavier than males.[1]

Feeding

The diet of oystercatchers varies with location. Species occurring inland feed upon earthworms and insect larvae.[1] The diet of coastal oystercatchers is more varied, although dependent upon coast type; on estuaries, bivalves, gastropods and polychaete worms are the most important part of the diet, whereas rocky shore oystercatchers prey upon limpets, mussels, gastropods, and chitons. Other prey items include echinoderms, fish, and crabs.

Breeding

Nearly all species of oystercatcher are monogamous, although there are reports of polygamy in the Eurasian oystercatcher. They are territorial during the breeding season (with a few species defending territories year round). There is strong mate and site fidelity in the species that have been studied, with one record of a pair defending the same site for 20 years. A single nesting attempt is made per breeding season, which is timed over the summer months. The nests of oystercatchers are simple affairs, scrapes in the ground which may be lined, and placed in a spot with good visibility. The eggs of oystercatchers are spotted and cryptic. Between one and four eggs are laid, with three being typical in the Northern Hemisphere and two in the south. Incubation is shared but not proportionally, females tend to take more incubation and males engage in more territory defence. Incubation varies by species, lasting between 24–39 days. Oystercatchers are also known to practice "egg dumping." Like the cuckoo, they sometimes lay their eggs in the nests of other species such as seagulls, abandoning them to be raised by those birds.[7]

Conservation

The Canary Islands oystercatcher became extinct during the 20th century. The Chatham oystercatcher is endemic to the Chatham Islands of New Zealand but is listed as endangered by the IUCN, while both the African and Eurasian oystercatchers are considered near threatened. There has been conflict with commercial shellfish farmers, but studies have found that the impact of oystercatchers is much smaller than that of shore crabs.

Species

Species in taxonomic order
Common name	Binomial	Image	Distribution
Magellanic oystercatcher	H. leucopodus Garnot, 1826		Southern South America
Blackish oystercatcher	H. ater Vieillot & Oudart, 1825		South America
Black oystercatcher	H. bachmani Audubon, 1838		West coast of North America
American oystercatcher	H. palliatus Temminck, 1820		North and South America
Canary Islands oystercatcher	H. meadewaldoi † Bannerman, 1913		Canary Islands
African oystercatcher	H. moquini (Bonaparte, 1856)		Southern Africa
Eurasian oystercatcher or Palaearctic oystercatcher	H. ostralegus Linnaeus, 1758		Europe, Asia and northern Africa
Pied oystercatcher	H. longirostris Vieillot, 1817		Australia
South Island oystercatcher	H. finschi Martens, 1897		New Zealand
Chatham oystercatcher	H. chathamensis Hartert, 1927		Chatham Islands
Variable oystercatcher	H. unicolor Forster, 1844		New Zealand
Sooty oystercatcher	H. fuliginosus Gould, 1845		Australia

Several fossil species are known, including Haematopus sulcatus (Brodkorb, 1955) from the early Pliocene of Florida. The oldest known fossil species is Haematopus palliatus, known from the Barstovian of Florida and Zanclean of North Carolina.

References

1. Hockey, P (1996) Family Haematopodidae (Oystercatchers) in del Hoyo, J.; Elliot, A. & Sargatal, J. (editors). (1996). Handbook of the Birds of the World. Volume 3: Hoatzin to Auks. Lynx Edicions. ISBN 84-87334-20-2
2. Lockwood, W B (1993). The Oxford Dictionary of British Bird Names. OUP. ISBN 978-0-19-866196-2.
3. Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 184, 286. ISBN 978-1-4081-2501-4.
4. Selous, Edmund (1905). The Bird Watcher in the Shetlands . London: J.M. Dent. p. 218 – via Wikisource.
5. Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 184. ISBN 978-1-4081-2501-4.
6. John B. Dunning Jr. (1992). CRC Handbook of Avian Body Masses. CRC Press. p. 98. ISBN 978-0-8493-4258-5.
7. "Birds Dumping Eggs on the Neighbors". Sciencedaily.com. 2011-06-03. Retrieved 2012-12-20.

External links

• ARKive – images and movies of the oystercatcher (Haematopus ostralegus)
• Oystercatcher videos on the Internet Bird Collection
• LIVE webcam at the seashore in Namsos, Norway 2013