The Crab Plover (left & above) is a dramatic wader of tidal
mudflats around the Indian Ocean. Its distribution is very localized. Indeed,
only nine nesting colonies are known in the entire world! Over 1500 pairs
nest in Iran, 300 pairs breed in the United Arab Emirates (where these
photos were taken), 85 pairs in Oman, 110 pairs in Saudi Arabia, and an
unknown number in Somalia (Rands 1996). It is an odd bird in many ways.
Its pied plumage recalls avocets but it nests in burrows and its heavy
bill is like those on Great Thick-knee Esacus recurvirostris or
Beach Thick-knee E. magnirostris. Like those latter species the
Crab Plover feeds almost exclusively on crabs, greedily dismembering the
unlucky prey it finds at low tide.
The Crab Plover is unique among waders by nesting in burrows that it digs itself. Some ornithologists have noted that this behavior is like auks. Yet its tarsal scutellation and the countershaded unpatterned gray down of its chicks is unlike other shorebirds; in these features it more closely resembles gulls. Sibley & Monroe (1980), relying heavily on DNA-DNA hybridization evidence, considered it just a very odd courser (Glareolidae). Most taxonomists elevate it to its own monotypic family. In fact Jehl (1968) divided all the waders into three groups on the basis of his study of downy chicks: the jaçanas & painted-snipes, the Crab Plover, and then all the remaining families. This division -- which elevates the Crab Plover to its own superfamily -- highlights its uniqueness and is considered the "standard" approach at present (Rands 1996).
Small flocks of Crab Plovers scatter more widely away from the breeding colonies the rest of the year, and I've enjoyed Crab Plovers in the Seychelles and the coast of Kenya. At high tide they use roosts with other shorebirds (photo at top of page) or wade out among the flamingos (below left at Khor al Beidah, United Arab Emirates). At low tide they forage on exposed mudflats like those at the mouth of Mida Creek, Kenya (below right; no Crab Plovers visible in this shot but the beachcomber is Steve Wilson).
Family book: rating IIII [out
of 5 possible]
Hayman, Peter, John Marchant & Tony Prater. 1986. Shorebirds: An Identification Guide to the Waders of the World. Croom Helm, London.
This book covers all the Charadriformes -- not just Crab Plover -- and so includes shorebirds (waders), stilts, avocets, jaçanas, thick-knees, plovers, and pratincoles. It is not a "family book" per se since its focus is on identification problems but it does include sections on "habits" and migratory or seasonal "movements." Breeding biology and similar topics are not covered here. However, the quality of the identification text more than makes up for this "defect" and adding broader topics would have made for a very fat book. John Marchant gets special credit for the text -- an upgrade from his 1977 guide (with Prater & Vuorinen) -- which surveys the literature well and is based on much original research. The book does rely on Hayman's paintings for illustrations and while they are generally good, I think that photos are a necessary requirement when dealing with the subtleties of shorebird identification. So use this book as an introduction to these families -- and the identification problems that exist -- but rely on other texts for state-of-the-art details.Because Hayman et al. (1986) is really aimed at field identification issues, the family is best summarized in the excellent text by Rand (1996) in the Handbook of the Birds of the World; it also contains a fine set of color photographs.
Other literature cited:
Jehl, J. R. 1968. Relationships in the Charadrii (shorebirds): a taxonomic study based on color patterns of the downy young. San Diego Soc. Nat. Hist. Memoir 3: 1-54.TOP
Rands, M. R. W. 1996. Family Dromadidae (Crab-Plover). Pp. 302-307 in del Hoyo, J., Elliott, A., & Sargatal, J., eds. Handbook of the Birds of the World vol. 3. Lynx Edicions, Barcelona.
Sibley, C. G., and B. L. Monroe, Jr. 1990. Distribution and Taxonomy of Birds of the World. Yale Univ. Press, New Haven, CT.
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