red knot (calidris canutus), a shorebird found in arctic tundra, spotted in bull island, dublin

red knot calidris canutus shorebird wading bird migratory arctic breeder bull island dublin coastal sandpiper fat reserves mudflats estuaries beach crustacean feeder mollusk eater wildlife birdwatching ornithology wetlands migration route longdistance flyer tundra nester sea water foraging plumage change high tide roost flock behavior wintering grounds low spring aquatic invertebrates rare sighting