Short-billed dowitcher

DISTRIBUTION AND HABITAT

There are three separate subspecies of short-billed dowitcher; all three breed separately in the North American Arctic. The westernmost of these subspecies migrates down the Pacific coast, while the central and eastern subspecies migrate through the Midwest and along the Atlantic coast. These latter two winter throughout the Caribbean and along both coasts of Central America, with a significant number of birds traveling further south to the northern coast of South America.

In the Arctic, short-billed dowitchers breed in the bogs and wet meadows of boreal forests. During migration and on their wintering grounds, they more frequently utilize saltwater habitats such as tidal mudflats, shoreline, salt pans, and lagoons. This latter fact also helps differentiate them from the long-billed dowitcher, which more frequently uses inland, freshwater habitat during the winter.

DIET

Dowitchers feed in a distinctive style, thrusting their long bills deep into sand or mud and pumping them up and down in a manner that has been frequently compared to a sewing machine. During migration and on their wintering grounds, mollusks, marine worms, insects, and other opportunistic foods such as horseshoe crab eggs make up the majority of their diet. On the Arctic breeding grounds, insects, spiders and other related invertebrates become the predominant food source. While the sewing-machine feeding manner is still used on occasion, many of these prey are simply picked from the surface.

LIFE CYCLE

The short-billed dowitcher, and in particular its breeding behavior, has not been well studied, in no small part because of the difficulty of locating its nests. The wetland habitat utilized during breeding, far wetter than that used by most other NJ shorebirds, is nearly intraversable for humans. It was not until 1957 that chicks belonging to the eastern population of short-billed dowitchers were first observed, and it was two more decades before the first nest was located.

After arriving on their breeding grounds, male short-billed dowitchers immediately begin re-establishing their territories from previous years. Singing to advertise a claimed territory is usually enough to deter intruders, but occasionally physical altercations do occur.

The females arrive a few days later, and monogamous pairs are formed almost immediately. It is thought that some pairs likely carry over from previous years, as occurs in many other shorebirds. The nest is a simple hollow on the ground and lined with feathers or vegetation, and the female almost always lays four greenish eggs. Both parents will incubate the eggs, but in a uniquely structured way: females typically brood during the day, while the male takes over at night. After about three weeks, the young hatch and are able to walk and feed within hours.

The female participates little in rearing, and some will even leave before the eggs have hatched. The male will remain for the first two weeks, defending the young and leading them to food. It is unknown exactly when young dowitchers fledge, but after fledging many will remain on the breeding grounds for notable lengths of time. The first juveniles begin to migrate south in late summer, but many will remain well into autumn.

CURRENT THREATS, STATUS, AND CONSERVATION

The lack of study of short-billed dowitchers, combined with the extreme difficulty of differentiating between short- and long-billed in the field, make an accurate assessment of population trends difficult. While the short-billed dowitcher is not currently considered threatened by any major conservation authority, most surveys indicate a significant decline in the eastern population, and the Midwest and Pacific populations are also believed to be in decline. It is believed that pesticide usage and the destruction of habitat are the causes behind these losses.

Coastal development throughout the migratory flyways and wintering areas continues to be a concern, as it is for most shorebird species. However, short-billed dowitchers are also at risk due to habitat destruction at their breeding grounds, a pressure that few other NJ shorebirds face. As these birds breed at the edges of boreal forests rather than the open tundra and rocky coasts favored by other threatened shorebirds such as red knots, logging activity and other commercial development have seriously damaged and fragmented large swaths of former breeding habitat. Protection of habitat appears to be the largest conversation priority for these birds to prevent further reduction of available breeding ground and allow populations to begin to recover.

Text written by Matthew Danihel in 2013.