Population size
The Bar-tailed godwit (Limosa lapponica) is a large wader. The migration of its subspecies Limosa lapponica baueri across the Pacific Ocean from Alaska to New Zealand is the longest known non-stop flight of any bird, and also the longest journey without pausing to feed by any animal. The round-trip migration for this subspecies is over 29,000 km (18,020 mi).
The Bar-tailed godwit is a relatively short-legged species of godwit. The adult has blue-grey legs and a long, tapering, slightly upturned bi-colored bill: pink at the base and black towards the tip. The neck, breast, and belly are unbroken brick red in breeding plumage, and dark brown above. Females' breeding plumage is much duller than males, with a chestnut to cinnamon belly. Breeding plumage is not fully apparent until the third year, and there are three distinguishable age classes; during their first migration north immature males are noticeably paler in colour than more mature males. Non-breeding birds seen in the Southern Hemisphere are plain grey-brown with darker feather centres, giving them a striped look, and are whitish underneath. Juveniles are similar to non-breeding adults but more buff overall with streaked plumages on flanks and breast.