Bird Feeding Glossary

Every term this site uses that is not everyday English, defined once and linked to the guide that goes deeper.

Bird feeding has picked up a vocabulary from three directions at once: ornithology, the hardware trade, and a century of accumulated backyard habit. This page defines the terms in plain English. Where a term deserves more than a sentence, the definition links to the guide that covers it properly.

A to C#

Aflatoxin. A toxin produced by Aspergillus molds growing on damp grain, particularly corn and peanuts. It is harmful to birds in small quantities. It is the main reason bird seed must be stored dry and never fed once it smells musty. See moldy seed.

Baffle. A dome, cone or cylinder fitted above or below a feeder to block climbing or dropping animals. The two common forms are the dome (hung above a hanging feeder) and the stovepipe or torpedo (fitted around a pole below the feeder). Sizing and height are what make it work. See baffles.

Brood parasite. A bird that lays its eggs in another species' nest and leaves the host to raise them. The brown-headed cowbird is North America's familiar example.

Bully bird. Informal term for a species that dominates a feeder and displaces others. Usually applied to grackles, starlings, house sparrows and sometimes blue jays. Not a scientific category, and worth remembering that most "bullies" are native birds doing normal bird things.

Caching. Storing food for later. Chickadees, titmice, nuthatches and jays all cache, which is why a chickadee may empty a feeder faster than its appetite explains.

Caged feeder. A feeder surrounded by a wire grid, typically about 1.5 inches (4 cm), that admits small birds and excludes larger ones and squirrels. See caged and selective feeders.

Cere. The fleshy area at the base of the upper bill in some birds. Rarely relevant at a feeder, common in field guides.

Crop. A muscular pouch in the throat where many birds store food before digesting it. It is why a mourning dove can vacuum up seed rapidly and digest it later somewhere safer.

Crop milk. A nutritious secretion produced in the crop of doves and pigeons and fed to nestlings. Unrelated to mammalian milk.

D to H#

Dimorphic (sexually dimorphic). A species in which males and females look different. Cardinals and house finches are strongly dimorphic; chickadees are not.

Eruption / irruption. An irruption is an irregular, large-scale southward movement of northern birds, driven by failures of the seed crops they rely on. Irruption years are when pine siskins, red-breasted nuthatches and purple finches appear far south of their usual winter range.

Fledgling. A young bird that has left the nest but is still dependent on its parents. Fledglings on the ground are usually not abandoned and generally should be left alone.

Gape. The mouth opening of a bird, and by extension the brightly colored mouth lining of a nestling that triggers parental feeding.

Grit. Small hard particles that birds swallow to help grind food in the gizzard. See grit, calcium and eggshells.

Gizzard. The muscular part of a bird's stomach that grinds food, assisted by grit.

Hopper feeder. A feeder with a covered reservoir that releases seed onto a tray by gravity as birds eat. See hopper feeders.

HPAI. Highly pathogenic avian influenza. See avian influenza and bird feeders.

Hull. The shell of a seed. "Hull-free" or "no-mess" blends are seeds sold with the shells already removed. See no-mess blends.

I to N#

Insectivore. A bird whose diet is mainly insects. Bluebirds, wrens and warblers are insectivores, which is why a seed feeder does nothing for them and mealworms do.

Lipid. Fat. The energy currency of winter bird feeding, which is why suet and sunflower dominate cold-weather advice.

Migratory Bird Treaty Act. US federal law protecting most native bird species, their nests and their eggs. It is why you may not interfere with a hawk at your feeder, and why native "problem" birds must be managed by exclusion rather than removal. Non-native species such as house sparrows, starlings and rock pigeons are not protected by it.

Mycoplasmal conjunctivitis. The formal name for house finch eye disease, caused by Mycoplasma gallisepticum.

Nectar. For feeding purposes, a solution of 4 parts water to 1 part white granulated sugar. No dye, no honey, no substitutes. See the hummingbird nectar recipe.

Nestling. A young bird still in the nest, unfeathered or partly feathered. Nestlings on the ground do need help, unlike fledglings.

Nyjer. A small black oil seed from Guizotia abyssinica, imported and heat-sterilized before sale, sometimes called thistle although it is not a thistle. See nyjer seed.

No-melt dough. Suet mixed with flour, cornmeal or oats so it holds its shape in warm weather. The summer answer to rendered suet going rancid. See suet.

O to R#

Passerine. A perching bird, order Passeriformes. Most feeder birds are passerines; woodpeckers, doves and hummingbirds are not.

Perch length. The length of the bar or ledge below a feeder port. Under about 3/4 inch (2 cm) admits small birds and excludes flocking blackbirds. One of the most consequential dimensions on a feeder and one of the least often published. See tube feeders.

Platform feeder. An open tray, hung, pole-mounted or set on the ground, that any bird can land on. Widest species appeal, worst weather protection. See platform feeders.

Port. The opening a bird feeds through. Sunflower ports are roughly 3/8 to 1/2 inch (10 to 13 mm); nyjer ports about 1/8 inch (3 mm).

Rendered suet. Animal fat that has been melted and strained to remove solids, which makes it far more stable than raw fat. See suet.

Resident. A species that stays in one area year-round, as opposed to a migrant. The Carolina wren is a resident, which is why hard winters hit it so hard.

S to Z#

Safflower. A white, thick-shelled seed that cardinals, chickadees and finches take, and that squirrels, grackles and starlings usually refuse. The classic "problem solver" seed. See safflower seed.

Snag. A standing dead or dying tree. Snags provide nest cavities and insect food and are the single most valuable thing you can leave in place for woodpeckers. See snags and dead wood.

Sterilized seed. Seed heat-treated so it cannot germinate. Nyjer is sterilized at import to prevent it establishing as a weed, which is also why old nyjer is dead nyjer: the oils go rancid and finches abandon it.

Suet. Strictly, hard fat from around the kidneys of cattle. In practice, any rendered fat cake sold for birds. See suet.

Tail prop. A ledge below a suet feeder that a woodpecker can brace its stiff tail feathers against. It makes a real difference for larger woodpeckers. See suet feeders.

Torpor. A state of reduced body temperature and metabolism used overnight by hummingbirds to survive cold. It is how an Anna's hummingbird overwinters in the Pacific Northwest.

Weight-activated feeder. A feeder whose ports close under the weight of a squirrel or a large bird. Effective against squirrels, less so against raccoons. See squirrel-proof feeders.

Zygodactyl. Having two toes forward and two back, the arrangement that lets woodpeckers and nuthatches grip vertical bark.