Food Habits

Feeding

Main Foods Taken

Terrestrial, freshwater, brackish, and marine invertebrates.

Microhabitat For Foraging

On coast feeds on beaches, tide flats, river mouths, lagoon margins, salt flats, and salt ponds. At beaches forages above and below mean high-water line, gathering food from above and below the sand surface, kelp (wrack), marine-mammal carcasses, or low foredune vegetation. Inland feeds on shores of lakes, reservoirs, ponds, braided river channels, and playas (mostly at seeps and along streams). Although at inland habitats most feeding is in shallow (1–2 cm deep) water or on wet mud or sand, on playas some foraging also occurs on dry flats.

Food Capture And Consumption

During daytime, feeds in typical plover fashion -- usually pauses, looks, runs, and then seizes prey from surface of beach or tide flat. Probing in sand, particularly at base of low growing plants, is used at times by Snowy Plovers foraging above high-tide line on California beaches (GWP) and, where there are concentrations of juvenile mole crabs (Emerita), below high tide line (D. George in litt.). Probing burrows for the beetle Bledius commonly observed on Oklahoma salt flats (Purdue 1976a, Grover and Knopf 1982). Shallow probing for brine fly larvae (Ephydridae) is employed on seeps at Mono Lake, CA, where the birds often shake the larvae before swallowing them (Swarth 1983).

Sometimes lowers head and charges with open mouth into dense aggregations of adult flies on ground, snapping bill at those flushed (Purdue 1976a). Usually snaps bill 2–3 times to crush captured flies before swallowing them (Swarth 1983). Plovers employ this charging method to capture isolated insects on California beaches. They also sometimes capture prey by hopping into clouds of kelp flies on coastal beaches (K. Neuman pers. comm.). J. Erbes (in litt.) has seen plovers jump up and capture moths and butterflies mid-air and then shake them vigorously before consuming them.

Another behavior sometimes preceding a feeding attempt is foot trembling in shallow water or on wet substrate (Feeney and Maffei 1991, R. Boyd pers. comm., JSW and JCW). At Ocean Beach, San Francisco Co., CA, wintering plovers frequently capture polychaetes during receding and low tides by employing the foot trembling behavior prior to pulling up worms (J. Erbes in litt.).

Appear to forage regularly at night; seen feeding on amphipods in near total darkness on a s. California beach (Lafferty 2001) and feeding after 22:00 during a full moon at Jalama Beach, Santa Barbara Co., CA (S. Hampton pers. comm.). On a tidal flat at Tokyo Bay, Japan, Kentish Plover feeding attempt and success rates were greater at night than during the day. As available foraging time was 1.7 times longer during night than day, Kentish Plovers could capture 3.7 times more prey (primarily nereid polychaetes and sand-bubbler crabs (Scopimera globosa) at night (Kuwae 2007). Comparable studies of Snowy Plover nocturnal and diurnal feeding ecology would be valuable.

Diet

During the breeding season on the s. California coast, beetles were found in 72%, adult flies in 44%, and insect larvae in 25% of 32 fecal samples of adult plovers. Rove beetles (Staphylinidae) were the most common beetle prey and long-legged flies (Dolichopodidae) and shore flies (Ephydridae) the primary dipteran prey. Fragments of other beetles (Carabidae and Cicindelidae), diptera (Anthomyiidae), hymenoptera (Braconidae), hemiptera (Saldidae), decapoda (Hippidae), and gastropoda (Nassaridae) were found in the samples. Feces from 3 fledglings contained rove beetles (3 samples), long-legged flies (2 samples), Braconidae (1 sample), and insect larvae (1 sample). The feces of one 2-week old chick contained only rove beetles. Adult plovers were also seen feeding on marine worms on several occasions (Tucker and Powell 1999).

Other information from Pacific Coast beaches and tidal flats identifies the following prey: mole crabs (Emerita analoga), crabs (Pachygrapsus crassipes), polychaetes (Neridae, Lumbrineris zonata, Polydora socialis, Scoloplos acmaceps), amphipods (Corophium spp., Ampithoe spp., Allorchestes angustus, and sand hoppers [Orchestoidea]), tanadacians (Leptochelia dubia), flies (Ephydridae, Dolichopodidae), beetles (Carabidae, Buprestidae, Tenebrionidae), clams (Nutricola sp.[formerly Transennella]), and ostracods (Reeder 1951, R. Wilson-Jacobs pers. comm., GWP).

Snowy Plover abundance on southern California beaches was positively correlated with the mean cover of wrack and abundance of wrack-associated invertebrates which are likely plover prey. These were identified as: taltrid amphipods (Megalorchestia californiana, M. benedicti, M. columbiana, M. corniculata); isopods (Tylos punctatus, Alloniscus perconvexus); beetles including a carabid (Dyschirius marinus), a tenebrionid (Phalaria rotundata), a hydrophilid (Cercyon lunger) three histeriids (Neopachylophus sulcifrons, Neopachylophus spp.), a curculionid (Emphyastes fucicola), seven staphylinids (Thinopinus pictus, Bledius fenyesi, Cafius seminitens, C. canescens, Potomalota opaca, Aleochara sulcicollis, and Thinusa maritima); and larvae and pupae of two dipterans (Coelopa vanduzeei, Fucellia costalis) (Dugan et al. 2003).

Prey consumed in San Francisco Bay salt-evaporation ponds include: flies (Ephydra cinerea), beetles (Tanarthrus occidentalis, Bembidion sp.), moths (Perizoma custodiata), and lepidopteran caterpillars (Feeney and Maffei 1991). At Great Basin saline and alkaline lakes plovers eat: flies (Ephydra hians, Thinophilus spinipes, T. latimanus, Mosillus bidentatus, Lamproscatella salinara, and Lispe sp.), beetles (Bembidion ephippigerum, Tanarthrus inyo, Bledius sp., Carpelimus sp., and Cicindelidae), hemipterans (Saldula arenicola), and brine shrimp (Artemia monica) (Swarth 1983, PWCP). At salt flats on the Great Plains plover prey are: flies (Ephydra sp.), beetles (Bledius sp., Cicindela sp.), and terrestrial insects blown onto flats, including a wide variety of grasshoppers, lepidopterans, and beetles (Purdue 1976a, Grover and Knopf 1982). Gulf Coast prey are described as: small crustaceans, mollusks, marine worms, aquatic insects, and seeds (Howell 1924).

Food Selection And Storage

Snowy Plovers do not cache food.

Nutrition And Energetics

No information.

Metabolism And Temperature Regulation

Individuals nesting in open, hot environments alleviate heat stress by panting, pteryloerection (elevating scapular, nape, and crown feathers), belly soaking (running through relatively deep water and intermittently preening ventral feathers), standing in water between incubation bouts, increasing frequency of parental shifts during incubation, and possibly restricting activities to near water (Purdue 1976b, Grant 1982). Body temperature of incubating Kentish Plovers increases with ambient temperatures in hot (> 30o C) environments; research suggests belly-soaking is used primarily to dissipate body heat of heat-stressed incubating adults and functions secondarily to cool overheated eggs (Amat and Masero 2007).

Drinking, Pellet-Casting, And Defecation

In osmotically stressful environments, Snowy Plovers may rely on water content of insectivorous diet and water-conservation behaviors, such as standing in pools, to avoid drinking saline solutions (Purdue and Haines 1977). When fresh water is available, drinks in repeated bouts by dipping bill in water and tilting head backward. Not reported to produce pellets, although this might be expected from individuals feeding on mole crabs on sandy beaches.