Food Habits

Main Foods Taken

Winter: small seeds, berries, buds, also insects. Migration: mainly seeds of grasses. Breeding season: small spiders and insects, also berries and occasional seeds.

Microhabitat For Foraging

Winter: feed on ground, after grasses have dropped their seeds, especially guinea grass (Panicum maximum; Stiles and Skutch 1989), also grass seeds on the stem. Breeding season: feed on ground (fallen grass seed), stems of tall grasses (seeds), low bushes (berries), herbs and other vegetation in tree canopy, ground level to 15 m (small spiders and insects). Males forage in trees near their singing sites, often alternately singing and feeding.

Food Capture And Consumption

Feeds alone in breeding season, in flocks on wintering grounds, with no obvious interaction among birds, which remain 0.2-1.0 m apart (Belize, RBP). Takes seeds from standing grass and herbs when it lands on a stem and shuffles upwards along the stem towards the seed head, the stem bending downward under the bird's weight; removes seeds from fruiting head. Also takes fallen seeds on ground. Eats as it finds food, husking small grass seeds with bill and tongue, gleaning small insects and spiders from leaves as it perches on small branches and moves through the canopy, beating larger insects against a branch. In winter (when uncommon in North America) and when returning in spring migration, feed on seeds on the stem and on the ground, and occasionally take seeds at feeding stations.

Major Food Items

In breeding season, small spiders and insects, including caterpillars, grasshoppers, bugs and beetles, also seeds of grasses and herbs (thistles Cirsium spp., dandelions Taraxacum spp., goldenrods Solidago spp.), and berries (blueberries Vaccinium spp., strawberries Fragaria spp,, blackberries Rubus spp., elderberries Sambucus canadensis spp.). As determined in samples of stomach contents, feed mainly on insects, such as caterpillars (e.g. browntail moth Euproctis chrysorrhoea, which have noxious hairs that cause dermatitis and respiratory problems in people), small beetles (including canker worms, click beetles, weevils and snout beetles or curulios), bugs, and many grasshoppers, locust borers, aphids and cicadas. Also take weed seeds, grain such as oats, and buds (Forbes 1883, Butler 1897, Barrows 1912, McAtee 1926, Taber and Johnston 1968).

In Michigan (RBP), upon arrival in spring, feed on twigs and leaves of flowering cottonwood trees and other aspen, oaks, beech and nut trees (alnut, shagbark and hickory); also on leaf buds, young leaves and flowers (elm, maple, cottonwood); on pollen (stuck to bills; seen when birds are caught in mist nets); and on caterpillars that feed on the unfolding leaves. Also take insects from leaf axils. In summer, bunting bills and feces become stained with berry juices (blueberries, strawberries, blackberries, serviceberries Amerlanchier anifolia). Buntings take many kinds of insects in trees and bushes, gleaning on leaves, flying from perch to perch, stripping an insect from the leaves, often singing as they feed. Perched on grass stems they take small seeds from the standing heads, the bird often bending the stem to reach the seeds. In summer they feed in open wetlands on stems of reed canary grass (Phalaris arundinacea) (males from several territories may visit and feed in these patches at the same time, with no aggressive interaction), in upland areas on little bluestem (Agropogon (Schizachyrium) scoparius). On lawns, feed on dandelion seeds, in cornfields (maize) on the pollen on tassels, and in soybean fields on small insects. On the ground they feed on small insects, spiders and small seeds, taking seeds from the surface with the bill, rather than scratching with the feet to uncover the seeds. Nesting birds feed their young spiders and spider egg cases and insects, including grasshoppers, small caterpillars, beetle larvae, mayflies and other winged insects (Bradley 1948, RBP).

In fall migration, feed in tops of bushes and trees, more often on seeds on standing grasses including big bluestem (Andropogon geradii), turkey bluestem (Calamagrostis canadensis), elephant grass (Pennisetum pupureum), oats (Avina sativa), Johnson grass (Sorhum halepense); also on seeds of legumes including vetch (Vicia villos, V. villosa), crimson clover (Trifolium incarnatum), beggarweed (Desmodium tortuosum), rattlebox or rattleweed (Crotolaria spectabilis), and indigo (Baptista tinctorum) (Trautman 1940, Taber and Johnston 1968, FMNH). Indeed the Indigo Bunting is known locally as "indigo bird" for its plumage color and its feeding behavior.

In winter, buntings take mainly small seeds of grasses. In Jamaica, In Dec. and Jan. when rains are infrequent, feed on stems of introduced guinea grass (Panicum maximum until stalks are stripped bare; then in dry season from Feb. to Apr. take seeds of trees such as logwood (Haematoxylon campechianum), dogwood (Cornus sp.), red birch (Betula nigra), and screwpine (Casuarina equisetifolia), and move in flocks to feed on grass seeds at feeding stations and use running water and bird-baths near the feeders (Johnston and Downer 1968). In Belize, feed on ground among bean plants, on seeding grass stems and in abandoned citrus orchards (RBP). Common around ricefields where they take seeds of weedy herbs and forbs, and grass and rice (buntings are called "riceys" in Belize: D. James). Buntings take seed at bird feeders both on migration and in winter (Fisk 1979).

Quantitative Analysis

No observational data and few specimen data. In summer, buntings in patches of black raspberries, nettles and goldenrod are difficult to observe; these areas are often full of small insects and serve as bunting nest sites (RBP). In an orchard with a cankerworm outbreak, all but one of 18 buntings fed on these insects, and canker worms made up 78% of the diet of the buntings (Forbes 1882, 1883, McAtee 1926). Forbes (1882: 204) noted, "...however well-marked the distinctive preferences of the various species may be, they are not inflexible, but but yield to the temptation of an unusual and easily-obtainable supply of some one kind of food."

None of the 254 labeled skin and skeletal specimans from Michigan in UMMZ have notes on contents of crop or stomach. Only four of 883 specimans in FMNH had labels with stomach contents; these four, taken in winter in Florida and Central America, had seeds. From field impression; opportunistic and non-specific feeding on small seeds, insects and berries as available.

No studies available on nutritional requirements. Nestlings have been reared with success on high-protein, high-calcium and other minerals diet developed for other songbirds (Lanyon 1979, Payne 1981, Yuri 2002). Captive buntings maintained in good condition for long periods (a year) on a diet of mainly grass seeds (millet) supplemented with live insects, vitamins, minerals (baked eggshells), fresh green vegetables, and fresh water (Payne 1981, RBP).

No data.

Drink infrequently and may obtain adequate water from insect and berry foods. Defecate several times per hour during the course of other activities.