Food Habits

Main Foods Taken

Insects, small crustaceans, mollusks, polychaetes; occasionally small fish.

Foraging Schedule

Feeds both by day and night (McNeil and Rompré 1995, Rompré and McNeil 1996) on ebb, flood, and slack tides. Foraging techniques and prey often vary with stages of tide and habitats (McNeil and Rompré 1995, Rompré and McNeil 1996); intensity of foraging and size of foraging territory may vary with habitat, prey type, and prey density (Douglas 1996). In addition, foraging techniques and habitats may vary depending on presence or absence of moonlight (McNeil and Rompré 1995, Rompré and McNeil 1996). In coastal lagoons of ne. Venezuela, Willets, defending winter feeding territories on mudflat zones where they forage visually on fiddler crabs (Uca spp.) both by day and on moonlit nights, abandon momentarily their territories and move to flooded areas on dark, moonless nights, when they change their feeding strategy and switch to tactile probing with nonterritorial individuals (McNeil and Rompré 1995, Rompré and McNeil 1996).

Microhabitat For Foraging

Western. During breeding season, found in shallow water and adjacent shore areas of wetland complexes in n. Great Plains (Ryan and Renken 1987). Along margins of ponds and lakes in e. Oregon (Mendenhall 1970). During nonbreeding season, found in varied California coastal types: mudflat, marsh, sandy beach, and rocky coast (Mendenhall 1970). In Saskatchewan, forages in shallow flooded areas of marshes and lake shorelines during spring and fall migration, primarily at depth of tarsus or less (Alexander and Gratto-Trevor 1997).

On sandy beaches, Tapping (see below) occurred at 7 cm water depth of wave outwash, and prey was within 5 cm of surface (Mendenhall 1970). Salicornia marshes at Sunset Beach (Orange Co.), CA (Reeder 1951). Mudflats at Palo Alto (Recher 1966). Muddy beaches, muddy sandy beaches, and at tide pools on the Inlet of La Paz, Baja California (Llinas Gutierrez and Galindo Jaramillo 1987).

Eastern. Feeds in oysterbeds and mudflats, sparsely vegetated Spartina salt-marsh habitat, around edges of salt marshes, beaches (Tomkins 1965, Hanson 1979), and along tidal creeks (Howe 1982). In se. Massachusetts, breeders forage regularly on sandy beaches (near nesting marshes), where they probe for mole crabs (Emerita spp.) along the wave outwash (A. Poole pers. comm.), as reported also from Virginia (Howe 1982).

Food Capture And Consumption

Diverse foraging methods. Several search-and-capture patterns described and defined (see Mendenhall 1970, Stenzel et al. 1976, Hansen 1979).

Touching (Mendenhall 1970), Picking (Hansen 1979), Peck or Multiple Peck (Stenzel et al. 1976), all seem to refer to same foraging type, although Peck may include Tapping (see below); most common method of prey capture (93% of prey captures during 664 min observations of 95 Willets; Stenzel et al. 1976). Prey captured visually with tip of bill from surface of mud; up to 60 items taken/min. Method used for gastropods, pelecypods worms [polychaetes, oligochaetes, nemertines], amphipods, and insects.

Tapping. Prey captured as submerged bill moves back and forth with up-and-down head motions. Prey located by tactile means and most often taken to shore to be subdued and swallowed; method used to capture small fish and worms. In Mexico, sometimes observed running along wave edge, with occasional shallow probing (L. Tibbitts pers. comm.).

Lifting. During bouts of Picking, foraging bird may lift or move aside substrate to pick food item from underneath (e.g., picks up eelgrass leaves to search for invertebrates; L. Tibbitts pers. comm.).

Probing. During bouts of Picking, foraging bird may thrust bill into substrate. Method used to capture pelecypods and worms, which are often taken to water and washed before being eaten (L. Tibbitts unpubl.).

Plowing. At Unare Lagoon, Venezuela, with turbid water conditions, Willets Plowed (i.e., 5- to 15-m rush with open bill partly or occasionally wholly under water) for small fish (as long as bill; McNeil and Rodriguez 1990). Unsuccessful chases after minnows in shallow water noted in Mexico (L. Tibbitts unpubl.).

Sometimes swims in California salt ponds and seizes prey near water surface (G. Page pers. comm.).

Frequency of use and exact application of these patterns differed between breeding and wintering areas and between normal daylight and dusk (Mendenhall 1970): Tapping not observed in summer, but Tapping used exclusively on sandy beaches in winter; Probing used on rocky coasts; at dusk, feeding methods changed from Touching to Tapping. Individual variation exists in application of different methods (Mendenhall 1970).

There appear to be size limits on diet related to handling, efficiency, and prey types. Items <6 mm long not consumed in winter while items <3 mm not consumed in summer; clams >2.5 cm difficult to handle (Mendenhall 1970). Swallows clams whole with series of head jerks and movements of tongue and mandibles; carries muddy clams to water and washes them. Grasps crabs by leg and shakes until body flies off, then eats leg and process repeated until legless carapace is swallowed whole. Western Willet took several minutes to excavate, wash, jab, shake, decapitate, and swallow toad (cf. Bufo boreas; Mendenhall 1970). Small fish carried to wet sandy shore, above water line, to peck, shake, and swallow (McNeil and Rodriguez 1990).

Western Willet chicks feed primarily on flies taken from surface of water and from vegetation and mud (Mendenhall 1970).

Major Food Items

Western. Breeding range (fresh water). At inland marshes, feeds primarily on predaceous insects, mostly beetles (water scavenger beetles [Coleoptera: Hydrophilidae: Tropisternus sp. adults, larvae of Berosus sp., Tropisternus sp., Enochrus sp.], diving beetles [Dytiscidae], and snout beetles [Curculionidae]) and other aquatic insects, spiders (Araneae), and fish (Cypriniformes; Mendenhall 1970). Nonbreeding range (salt water). On Sunset Beach (Orange Co.) CA, shorecrab (Hemigrapsus sp.) occupied largest volume of stomach contents (n = 2), while cirratulid sandworms made up 50% of volume of 1 stomach (Reeder 1951). At Inlet of La Paz, Baja California, Mexico, primary prey were brachyuran crabs Uca princeps and U. crenulata (Decapoda: Ocypodidae; Llinas Gutierrez and Galindo Jaramillo 1987). At San Francisco Bay, CA, clam (Macoma sp.) taken on mudflats and crab (Pachygrapsus sp.) on rocky coasts (Mendenhall 1970); elsewhere on bay, clam (Gemma gemma; Pelecypoda), nereid worm (Neanthes sp.; Polychaeta: Nereididae), and dog whelk (Ilyanassa obsoleta; Caenogastropoda, Nassariidae) recorded (Recher 1966). Prey identification from 45 pellets include following as prominent (present in >10 pellets) prey: clams Gemma gemma and Protothaca staminea; mussel Mytilus sp. (Unionidae); amphipods Allorchestes angustus and Orchestia traskiana (Talitridae); and brachyuran crab Hemigrapsus oregonensis (Grapsidae; Stenzel et al. 1976). Often seen taking mole crabs along sandy beaches of California, Oregon, and Washington (N. Warnock pers. comm.).

Eastern. Along Georgia and Virginia coasts, chief prey include fiddler crabs (Uca minax, U. pugnax, U. pugilator, Sesarma cinerea, S. reticulatum) and mole crabs (Emerita talpoida; Tomkins 1965, Howe 1982). One young Willet (approximately 1 wk old) ate small snail (Littorina irrorata; Tomkins 1965). Diet in Nova Scotia more diverse including Corophium volutator, gastropods, pelecypods, polychaetes, oligochaetes, amphipods, fish, and insects (Hansen 1979).

Quantitative Analysis

No information.

Generalist feeder. Detects prey by sight and touch. Employs wide repertoire of foraging techniques under different foraging conditions. In tidal lake, captures amphipods with scissoring motion on ebb tide, but feeds on tube worms with a stitching motion on flood tide (Douglas 1996). Not known to store food.

Forages both day and night (Stenzel et al. 1976, Robert et al. 1989, McNeil et al. 1990). At Bolinas Lagoon, CA, feeds at night during winter (Nov–Feb; wet season) but not during fall (Jul–Oct; dry season; Stenzel et al. 1976). At Chacopata Lagoon, Venezuela, more Willets forage during darkness than during daylight in autumn; equal propor-tions forage day and night during winter and spring, but more birds feed during both day and night when accumulating fat for spring migration; these seasonal changes in foraging behavior mirror seasonal changes in fat content (r = 0.690, p < 0.05, n = 7; Rompré and McNeil 1994).

Young chicks appear substantially homoiothermic from day of hatching (Tomkins 1965), but see Breeding: parental care, below.

Known to cast pellets (Tomkins 1965, Stenzel et al. 1976, Below 1979). Willet’s behavior when doing so resembles retching actions of regurgitation, lasting 12–25 min, with fluid dripping from bill and flicking bill sideways (Below 1979).