Diet and Foraging

Main Foods Taken

The Hudsonian Godwit feeds mainly on invertebrates and plant material. During migration, it rely heavily on plant tubers at inland sites (5 Alexander, S. A., K. A. Hobson, C. L. Gratto-Trevor, and A. W. Diamond (1996). Conventional and isotopic determination of shorebird diets at an inland stopover: the importance of invertebrates and Potamogeton pectinatus tubers. Canadian Journal of Zoology 74:1057-1068. Close ).

Microhabitat for Foraging

Few quantitative data. On breeding grounds, the bird feeds mainly in wet parts of sedge marsh and along vegetated edges of shallow tundra pools; pairs nesting near the coast and premigratory flocks feed on exposed mud on tidal flats (2 Hagar, J. A. (1966). Nesting of the Hudsonian Godwit at Churchill, Manitoba. Living Bird 5:5-43. Close , CSE). In the Churchill area, it often feeds in the same places as the Stilt Sandpiper, Short-billed Dowitcher, and Lesser Yellowlegs . During fall migration at Quill Lakes, Saskatchewan, it is typically seen feeding in flooded areas; slightly > 50% of time spent in water shallower than length of the birds' tarsi, the rest of the time in deeper water; not seen feeding in areas that were dry or merely covered with a film of water (6 Alexander, S. A., and C. Gratto-Trevor (1997). Shorebird migration and staging at a large prairie lake and wetland complex: The Quill Lakes, Saskatchewan. Canadian Wildlife Service Occasional Papers no. 97. Environment Canada, Ottawa, Ontario, Canada. Close ). In spring, at Cheyenne Bottoms, Kansas, 82% of 244 birds were found in open shallow water, 17% at water-mud interface; the mean water depth for 235 foraging birds was 5.1 cm ± 3.1 SD; the bird generally avoided vegetation (117 Helmers, D. L. (1991). Habitat use by migrant shorebirds and invertebrate availability in a managed wetland complex. Unpubl. Master's Thesis, Univ. of Missouri, Columbia. Close ). At Lagoa do Peixe, Brazil, higher numbers were found in flooded areas at least several centimeters deep than in areas with exposed mud or wet sand; in this study, it occasionally used pools in sand dunes for roosting but never fed on the beach (148 Lara Resende, S. de M. and F. Leeuwenberg (1987). Ecological studies of Lagoa do Peixe. WWF/US. Close , 38 Lara Resende, S. de M. (1988). Nonbreeding strategies of migratory birds at Lagoa do Peixe, Rio Grande do Sul, Brazil. Master's Thesis, Cornell Univ., Ithaca, NY. Close ).

Food Capture and Consumption

The Hudsonian Godwit obtains most food by probing with at least one-quarter of bill inserted into the mud, but also by pecks in which just the tip enters the mud or prey is plucked from water column, mud surface, or vegetation (6 Alexander, S. A., and C. Gratto-Trevor (1997). Shorebird migration and staging at a large prairie lake and wetland complex: The Quill Lakes, Saskatchewan. Canadian Wildlife Service Occasional Papers no. 97. Environment Canada, Ottawa, Ontario, Canada. Close , JK). It often inserts its bill deep into the mud and submerges its head when feeding in water; it may probe rapidly like a dowitcher (34 Wright, G. (1987). Hudsonian Godwit in Devon. British Birds 80:492-494. Close ). Captured prey items are passed along the bill rapidly (37 Wetmore, A. (1926). Observations on the birds of Argentina, Paraguay, Uruguay, and Chile. United States National Museum Bulletin 133:1–448. Close ). Adults guarding small chicks glean insects from vegetation.

On vegetated pond margins, the Hudsonian Godwit walks slowly in water up to its belly, dipping its whole head in the water, in a monotonous motion: step-dip, step-dip; it may make multiple dips from one place. Feeding birds stop periodically to preen or to look around; also when other shorebirds call. It will wade or swim through deep water. On muddy substrates, it tilts its whole body forward to probe, often close to the base of vegetation or partially submerged rocks if present. It often runs between making pecks on mudflats, suggesting use of visual cues more than when feeding underwater. When feeding on tubers, it has a distinctive manner of pushing its bill into the mud and rotating it to make a small hole by the plant, often making several probes in quick succession (4 Alexander, S. A. (1994). Inland staging by shorebirds during autumn migration: diet, prey availability, body composition, and flight range. Master's Thesis, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Close , 5 Alexander, S. A., K. A. Hobson, C. L. Gratto-Trevor, and A. W. Diamond (1996). Conventional and isotopic determination of shorebird diets at an inland stopover: the importance of invertebrates and Potamogeton pectinatus tubers. Canadian Journal of Zoology 74:1057-1068. Close ).

The bird presumably locates food by touch while probing and by sight when gleaning. The bill tip is reportedly “flexible” (L. C. Sanford in 31 Bent, A. C. (1927). Life histories of North American shorebirds, Part 1. U.S. Nat. Mus. Bull. 142. Close ) implying at least one rhynchokinetic joint that may help individuals grasp food items buried deep in mud.

Few data on feeding performance, but success rates of 48–71% recorded for 4 birds feeding in Carex marsh at Susitna Flats, Alaska (L. Tibbitts, unpublished data), while success rates of 0-13% (n = 217) were recorded at wintering sites across southern South America (Senner and Senner, unpublished data). One bird in Britain ate 40–50 prey items/min (11 Grieve, A. (1987). Hudsonian Godwit: new to the Western Palearctic. British Birds 80:466-473. Close ).

Few data. One study on breeding grounds at Churchill (n = 12 birds; 149 Baker, M. C. (1977). Shorebird food habits in the eastern Canadian Arctic. Condor 79:56–62. Close ) found the majority of stomach contents to consist of insect larvae (Diptera: Cyclorrapha and Tipulidae) and beetles (Coleoptera: adult and larval Chrysomelidae, Donacia, and adult Dysticidae Hygrotus); > 50% of food items were Cyclorrapha larvae, with < 10% each of Tipulidae larvae, adult Donacia, larval Donacia, adult Hygrotus, unidentified snails (Gastropoda), and seeds. In that study, the Hudsonian Godwit tended to select prey approximately 3–6 mm in length (mean length approx. 5 mm), but took items ranging from 2 to > 10 mm in length.

Gizzards of 5 birds collected on breeding grounds at Mackenzie River delta, Northwest Territories, contained mostly invertebrates (Diptera: Tabanidae larvae, Trichoptera larvae, Hemiptera adults, Hymenoptera adults) and small snails (1–4 mm). Stable isotope analyses of tissue from these birds also suggested that invertebrates were main food source (5 Alexander, S. A., K. A. Hobson, C. L. Gratto-Trevor, and A. W. Diamond (1996). Conventional and isotopic determination of shorebird diets at an inland stopover: the importance of invertebrates and Potamogeton pectinatus tubers. Canadian Journal of Zoology 74:1057-1068. Close ).

During fall migration, tubers of sago pondweed (Potamogeton pectinatus) made up the majority of the diet at Quill Lakes: 94% of food volume in the esophagus and proventriculus (n = 20 birds, 114 food items) and 66% of items in the gizzard (n = 17 birds, 402 food items). Analyses of stable isotope ratios suggested that sago pondweed constituted 61–74% of the diet at this site. Despite this apparent discrepancy, 95% confidence intervals around this estimate encompassed the estimate based on gut-content analysis. Clearly, plant tubers are a major portion of the diet at this staging site; it is possible that a carbohydrate-rich diet may be especially important for godwits preparing to embark on long migratory flights (4 Alexander, S. A. (1994). Inland staging by shorebirds during autumn migration: diet, prey availability, body composition, and flight range. Master's Thesis, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Close ). Other food items in esophagus-proventriculus of these birds included: seeds (2% of volume; found in 3 individuals) and Diptera: Chironomidae larvae (4%; 1). And in the gizzard, seeds (mostly Potamogeton and Scirpus spp.; 27% of food items; found in 11 individuals), Eleocharis parvula tubers (1%; 1), Diptera: Chironomidae larvae (2%; 2), Coleoptera larvae: Dytiscidae (< 1%; 1), Haliplidae (< 1%; 1), Hydrophilidae (< 1%, 1), Hemiptera: Corixidae (2%; 2), and Orthoptera: Acrididae (2%; 1). Seeds in the diet showed no evidence of digestion, suggesting they may have been eaten to help grind other food (5 Alexander, S. A., K. A. Hobson, C. L. Gratto-Trevor, and A. W. Diamond (1996). Conventional and isotopic determination of shorebird diets at an inland stopover: the importance of invertebrates and Potamogeton pectinatus tubers. Canadian Journal of Zoology 74:1057-1068. Close ).

At Samborombón Bay, Argentina, the diet was primarily nereid worms (Laeonereis acuta and Neanthes succinea); fiddler crabs (Uca uruguayensis) made up 0.6% of food items, but more important in terms of biomass (145 Ieno, E. (2000). Las comunidades bentónicas de fondos blandos del norte de la Provincia de Buenos Aires: Su rol ecológico en el ecosistema costero. Tesis Doctoral, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina. Close ). At Punta Loyola, Patagonia, Argentina, bivalve Darina solenoides was eaten (150 Bala, L., M. Hernandez, and M. C. Baarck (1998). Análisis de la dieta de Limosa haemastica, en Punta Loyola, Santa Cruz. Reunión Argentina de Ornitología 3. Close ).

Other reports of foods include earthworms (Annelida), insects (horseflies [Tabanidae], mosquitoes [Culicidae]), mollusks (including Macoma balthica), crustaceans (including amphipods), and other small invertebrates (151 Forbush, E. H. (1925). Birds of Massachusetts and other New England states Part 1. Commonwealth of Massachusetts. Massachusetts Dept. Agriculture: Commonwealth of Massachusetts. Close , 152 Martini, A. C., R. I. G. Morrison, W. A. Glooschenko, and R. Protz (1980). Coastal studies in James Bay, Ontario. Geoscience Canada 7:11–21. Close , 34 Wright, G. (1987). Hudsonian Godwit in Devon. British Birds 80:492-494. Close ); predominantly polychaete worms on intertidal mudflats of Tierra del Fuego (8 Piersma, T., J. van Gils, and P. Wiersma (1996). Family Scolopacidae (sandpipers, snipes and phalaropes). In Handbook of the Birds of the World Volume 3: Hoatzin to Auks (J. del Hoyo, A. Elliott, and J. Sargatal, Editors). Barcelona, Spain: Lynx Edicions. pp. 444–533. Close ); crowberries (Empetrum nigrum) on breeding grounds in Alaska (B. McCaffery and C. Harwood, personal communication).

Little information. The Hudsonian Godwit apparently feeds opportunistically. Baker (149 Baker, M. C. (1977). Shorebird food habits in the eastern Canadian Arctic. Condor 79:56–62. Close ) found evidence that individuals select prey on average larger than expected based on size range available; however, prey taken were not the largest available. In Argentina, the godwit was found to select the largest (40–60 mm) nereid worms (145 Ieno, E. (2000). Las comunidades bentónicas de fondos blandos del norte de la Provincia de Buenos Aires: Su rol ecológico en el ecosistema costero. Tesis Doctoral, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina. Close ). A higher incidence of invertebrates in the diet during the breeding season than during migration may reflect low availability of tubers on breeding grounds, but also could indicate selection for foods rich in protein and calcium while breeding; a high incidence of snails in the diet from Mackenzie River delta, in particular, may indicate selection for calcium-rich food (5 Alexander, S. A., K. A. Hobson, C. L. Gratto-Trevor, and A. W. Diamond (1996). Conventional and isotopic determination of shorebird diets at an inland stopover: the importance of invertebrates and Potamogeton pectinatus tubers. Canadian Journal of Zoology 74:1057-1068. Close ).

Caching unknown.

There is little information on the Hudsonian Godwit; see Migration: Control and Physiology. The larger congener, the Bar-tailed Godwit (Limosa lapponica), prior to migration shows a body mass increase of 6.0 g/d (153 Kersten, M. and T. Piersma. (1987). High levels of energy expenditure in shorebirds; metabolic adaptations to an energetically expensive way of life. Ardea 75:175-187. Close ). Daily energy expenditure of 3.5-d-old Hudsonian Godwit chicks raised in captivity can range from 12.1 to 50.3 kJ/d (with mass of chicks, respectively, 25.2 and 32.7 g), and increases to an average of 297 kJ/d in 17-d-olds (K. Krijgsveld, personal communication; 154 Williams, J. B., B. I. Tieleman, G. H. Visser, and R. E. Ricklefs (2007). Does growth rate determine the rate of metabolism in shorebird chicks living in the arctic? Physiological and Biochemical Zoology 80:500–513. Close ). Net energy intake in adults of the larger Bar-tailed Godwit (Limosa lapponica) estimated as 610–886 kJ/d (153 Kersten, M. and T. Piersma. (1987). High levels of energy expenditure in shorebirds; metabolic adaptations to an energetically expensive way of life. Ardea 75:175-187. Close ). Based on field observations, the bird is estimated to consume 0.21 mg AFDW (ash-free dry weight)/s, although this estimate may be low (145 Ieno, E. (2000). Las comunidades bentónicas de fondos blandos del norte de la Provincia de Buenos Aires: Su rol ecológico en el ecosistema costero. Tesis Doctoral, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina. Close , E. Ieno, personal communication). Using allometric relationships, the mean metabolic rate of adults is estimated at 273 kJ/d (145 Ieno, E. (2000). Las comunidades bentónicas de fondos blandos del norte de la Provincia de Buenos Aires: Su rol ecológico en el ecosistema costero. Tesis Doctoral, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina. Close ).

No information.

Little information. Pellet-casting has not been reported, but is found in many large shorebirds; incidence may depend on diet. The Hudsonian Godwit bends its legs at the tibiotarsal joint in a slight squat while defecating.