Food Habits

Main Foods Taken

At breeding grounds and interior sites: insects such as midge fly and larvae, aquatic or moist soil worms, and small burrowing crustacea (Cogswell 1977). Coastal areas: polychaetes, bivalves, and amphipods. Contents of 99 Long-billed Dow-itchers collected throughout the West, 86% animal matter, 14% plant matter (Sperry 1940).

Microhabitat For Foraging

Shallow water on coastal mudflats, interior wetlands, and wet meadows, especially on breeding grounds (Kessel 1989); generally feeds in substrates with soft mud bottom. (For information on invertebrate populations, see Diet, below). In sandy-bottom habitats, sand reduced success in prey capture in comparison to muddy sites (Quammen 1982). In pastures along coastal California, abundance negatively correlated with vegetation height (Colwell and Dodd 1995). Water height important in determining where species feeds: managed wetlands of South Carolina, 4–5 cm deep (Weber and Haig 1996); playa lakes of Texas, 0–16 cm (Davis and Smith 1998a); flooded rice fields in Central Valley, CA, 2–8 cm (Elphick and Oring 1998).

Food Capture And Consumption

In Long-billed and Short-billed dowitchers, 2 feeding behaviors described: jabbing and probing; probing behavior a distinctive “sewing machine” motion. At tip of bill, possess numerous tactile receptors, Herbst corpuscles; these help locate prey by touch (Burton 1972). Forages little at night during winter, more during fall migration (Dodd and Colwell 1996). Eyes of Short-billed Dowitcher have intermediate rod/cone ratios for vision both day and night (Rojas de Azuaje et al. 1993). Both species find prey by tactile probing in surface layers of sediment, often probing deeper than depth of their bills (Quammen 1982); head of Long-billed Dowitcher often below surface of water (Young 1989).

Breeding

Chironomid larvae important at Beaufort Sea littoral zone (Connors 1984). Larvae of insects, plant matter, seeds, and small stones found in stomachs of young Long-billed Dowitchers from Lawrence Bay, Russia; on Wrangel I., Russia, caterpillars, beetles, plant material, and sand found in stomachs (Portenko 1981); Chironomidae on St. Paul I., AK (Bent 1927). Two stomachs from Chukotka Peninsula, Russia, contained almost exclusively Chironomid larvae, with 3% vegetable matter, generally seeds (Dement’ev and Gladkov 1969).

Wintering And Migrating

At Bolinas Lagoon, CA, sedentary polychaetes, particularly Capitella spp., and tube-dwelling amphipods (mostly Corophium spp.) most common prey in fecal samples; polychaetes, ostracods, copepods, bivalves, and oligochaetes also commonly observed (Stenzel et al. 1983). In sample of 99 Short-billed and Long-billed dowitchers collected from Alaska to Texas (Sperry 1940), larval insects most common prey items, including Diptera (58%), Coleoptera (11%), and other (2%), while other prey items include crustaceans (8%), mollusks (4%), and marine worms (3%); much of collecting done at freshwater sites. In Newport Bay, CA, most common prey of dowitchers (both species): Streblospio, polydorids, capitellids, oligochaetes, followed by mollusks (Utriculastra, Tryonia, Assiminia), bivalves, and crustaceans (Pontongenea, Corophium, Rudilemboides; Quammen 1984). In San Francisco Bay, CA, important invertebrate prey included Polychaeta, Cumacea, and bivalves (Gemma gemma, Macoma balthica, Potamocorbula amurensis, and Mytilidae); preferences highest for Polychaeta and Cumacea (J. Takekawa and S. Warnock unpubl.). Percent occurrence (spring, n = 75; fall, n = 94) of major food items in all samples from High Plains region of Texas contained Chironomidae (85.1, 70.7), Coleoptera (27.1, 81.3), Hydrophilidae (13.8, 77.3), Odonata (7.4, 10.7), Oligochaeta (20.2, 10.7), Hirudinea (19.1, 14.7), Gastropoda (12.8, 46.7), Planorbidae (3.2, 46.7), Cladocera (2.1, 10.7), Conchostraca (2.1, 14.7), and seeds (29.8, 37.3); compared with American Avocet (Recurvirostra americana), Least Sandpiper (Calidris minutilla), and Western Sandpiper (C. mauri), only shorebird that preferred Planorbidae; preference for foods differed significantly between seasons (Davis and Smith 1998a); consumed prey size in proportion to availability (Davis and Smith 1997). Major item Chironomidae, overlapping 81% with American Avocet (Recurvirostra americana), 59% with Stilt Sandpiper, but only 2% with Lesser Yellowlegs (Tringa flavipes), Wilson’s Phalarope (Phalaropus tricolor), and Killdeer (Charadrius vociferus), and 1% with Baird’s Sandpiper (Calidris bairdii; Baldassarre and Fischer 1984).

Other Foods

Plant matter and seeds found in collected specimens (Sperry 1940, Portenko 1981, Dement’ev and Gladkov 1969, Davis and Smith 1998a); 12% of diet in fall and 5% in spring from Long-billed Dowitchers in Texas (Davis and Smith 1998a).

Extracted lipid content (3–10% wet weight) from a sample of Long-billed Dowitchers (n = 45) not significantly different between sexes and highly correlated with mass; lipid declines over winter (White and Mitchell 1990). Percent lipids in muscles and carcasses of Long-billed Dowitcher collected in Jan at Sacramento NWR, CA (4.6% and 7.9% respectively) and at Delevan NWR, CA (3.6% and 7.3%; Custer and Myers 1990). Spent 75–90% feeding during spring (Davis and Smith 1998b).

Few data on metabolism and temperature regulation; little studied. Greatest proportion of time spent feeding during midday, because energy demands of thermoregulation and unsuccessful feeding attempts are too costly (Davis and Smith 1998b).

Observed drinking in brackish water by dipping and raising bill, tilting head back. Likely casts pellets, but no information.