Red knot  (Calidris canutus)

Authenticated (24/06/08) by Maurine Dietz, Senior Scientist, Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen,
http://www.rug.nl/biologie/onderzoek/onderzoekgroepen/dieroecologie/index; and by Jan van Gils, Department of Marine Ecology, Royal Netherlands Institute for Sea Research (NIOZ),
http://www.nioz.nl/nioz_nl/6ed7dac0ba63c2db76477364f18ee021.php

• Crustaceans: diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
• Echolocation: detecting objects by reflected sound. Used by bats and odontocete cetaceans (toothed whales, dolphins and porpoises) for orientation and to detect and locate prey.
• Invertebrates: animals with no backbone.
• Molluscs: a diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
• Mudflats: A large area where parts of the sea bottom fall dry at low tides and thus become available for birds to forage on. A good example is the Wadden Sea (in the Netherlands, Germany and Denmark). These unique tidal areas are very rare in the world and in general very important for coastal foraging birds.
• Muscular gizzard: in birds, the stomach can be divided in two parts. The first part is the glandular stomach that secrets digestive enzymes; the second part is the muscular gizzard that mechanically processes food. Depending on species and diet, some parts of the stomach can be more important. In knots, the glandular stomach is relatively unimportant. For the largest part of the year (outside the breeding season), food processing depends largely on the muscular gizzard that crushes the shells or other hard parts of the food. In knots, the actual digestion takes place in the intestines.
• Primaries: in birds, the outer flight feathers.
• Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
• Tundra: treeless grassland between the icecap and the tree line of Arctic regions, with vegetation consisting of lichens, grasses, sedges and dwarf woody plants.

1. IUCN Red List (June, 2008)
   http://www.iucnredlist.org
2. del Hoyo, J., Elliott, A. and Sargatal, J. (1996) Handbook of the Birds of the World. Volume 3: Hoatzin to Auks.Lynx Edicions, Barcelona.
3. CMS (June, 2008)
   http://www.cms.int
4. AEWA (June, 2008)
   http://www.unep-aewa.org
5. Canada’s Aquatic Environments (December, 2004)
   http://www.aquatic.uoguelph.ca/birds/speciesacc/accounts/sandpipe/canutus/account.htm
6. Bird Guides (December, 2004)
   http://www.birdguides.com/species/species.asp?sp=057063
7. Enature (December, 2004)
   http://www.enature.com/fieldguides/detail.asp?allSpecies=y&searchText=Red%20knot&curGroupID=1&lgfromWhere=&curPageNum=1
8. Van Gils, J.A., Piersma, T., Dekinga, A. and Battley, P.F. (2006) Modelling phenotypic flexibility: an optimality analysis of gizzard size in red knots (Calidris canutus). Ardea, 94: 409 - 420.
9. Piersma, T., van Aelst, R., Kurk, K., Berkhoudt, H. and Maas, L.R.M. (1998) A new pressure sensory mechanism for prey detection in birds: the use of principles of seabed dynamics?. Proceeding of the Royal Society of London, Series B, 265: 1377 - 1383.
10. State of New Jersey (December, 2004)
    http://www.nj.gov/dep/fgw/ensp/pdf/end-thrtened/redknot.pdf
11. Baker, A.J., González, P.M., Piersma, T., Niles, L.J., De Lima Serrano do Nascimento, I., Atkinson, P.W., Clark, N.A., Minton, C.D.T., Peck, M.K. and Aarts, G. (2004) Rapid population decline in red knots: fitness consequences of decreased refuelling rates and late arrival in Delaware Bay. Proceeding of the Royal Society of London, Series B, 271: 875 - 882.
12. Van Gils, J.A., Piersma, T., Dekinga, A., Spaans, B. and Kraan, C. (2006) Shellfish dredging pushes a flexible avian top predator out of a marine protected area. PLoS Biology, 4: 2399 - 2404.