Residents, Migrants, Vagrants… Waders or Shorebirds?

By Keith Hutton on October 21, 2015 in Other

Waders are also called shorebirds, and both names are good descriptions for most of them. However, there are many that never go near the shore, and others that never wade. About eighty species have been recorded in Australia. Not all of these are present at one time, or in any one season. Only eighteen species are breeding residents and most of the rest are either non-breeding migrants or rare vagrants. Ten of the residents breed only in Australia. Almost half the waders seen in Australia migrate here regularly for their non-breeding season, and all except one are trans-equatorial migrants that breed in the northern hemisphere and come to Australia in summer; the exception is the Double-banded Plover, which breeds in New Zealand and winters in Australia. Finally, there are twenty-five vagrant wader species – largely trans-equatorial migrants that reach Australia so rarely, or in such small numbers, that the chance of coming across them is remote. Waders are well represented in the Sydney region with twenty-seven species present.

Waders have relatively long legs and they feed in shallow water or on the ground, where the majority of them nest. Beyond these characteristics there are more differences than similarities, which is not unexpected in a cosmopolitan group of over two hundred species worldwide. Interestingly, waders exhibit a wide range of bill shapes and sizes that relate to feeding methods; some have short bills and some have long bills; some have straight bills and others have curved bills – some down, some up. The Wrybill in New Zealand has a bill that bends sideways and the Spoon-billed Sandpiper in Asia has a bill with a flattened tip. Some waders look the same throughout the year and many others have bright, colourful breeding plumages. Sexes are usually similar but males may be more colourful than females, or vice versa.

Waders are well represented in all continents in the world except Antarctica, with only a few species recorded on subantarctic islands. Most breed in the northern hemisphere and migrate south each year. Many habitats are exploited, either on the coast or inland. Rocky shores, beach and dune shores, and tidal flats are preferred coastal habitats, while most waders inland prefer lakes, marshes and swamps.

All waders are opportunistic predators and different species select preferred prey from a range of options such as molluscs, crustaceans, worms, spiders, or insects and their larvae. Small fish and reptiles, frogs and some birds’ eggs, seeds and vegetable matter are also taken by some species. Availability and abundance of prey, agility, leg length, design of the bill, and the ability to swim or not all affect food items selected by waders.

Hunting and disturbance, destruction and alteration of their habitat, and pollution have affected waders on their breeding grounds, where they migrate through Asia, and on their non-breeding grounds in Australia. Many migratory waders are disappearing and some are critically endangered. The declines continue despite ongoing international cooperative conservation efforts throughout the East Asian-Australasian Flyway.