71 ORNITHOLOGIST A person who studies birds. PELLET A hard lump of indigestible bits of food, such as fur and bones, that birds regurgitate. PLUMAGE A bird’s feathers. POWDER DOWN Special feathers on some birds that disintegrate to form a powder, which the bird uses to clean its plumage. PREDATOR An animal that kills another animal for food. PREENING The way in which birds keep their feathers in good condition, drawing them through their beaks to clean them. PREY An animal that is hunted and killed by another animal. PRIMARY FEATHERS The long flight feathers on the outer half of the wings, used for steering and turning. QUILL The long, hollow central shaft of a bird’s feather. REGURGITATE To bring food that has been swallowed back up into the mouth again, often to feed the young. ROOST To settle down to rest, normally overnight. SCAVENGER A bird, such as a vulture, that searches for dead animals to eat. HIDE A structure or small building where people can hide to watch birds without disturbing them. INCUBATION Providing constant warmth for eggs so that chicks can develop inside them. Most birds incubate their eggs by sitting on them to keep them warm. INVERTEBRATE A type of small animal that has no backbone, such as a worm. IRIDESCENT The glittering sheen on some feathers and other objects that appears to change colour depending on the direction of the light. KEEL A large, plate-like extension of a flying bird’s breastbone, which anchors its powerful wing muscles in place. KERATIN A type of protein from which feathers, hair, nails, and hooves are made. MANDIBLE One of the two parts of a bird’s beak (bill). The upper mandible is the top part, and the lower mandible is the bottom part. MIGRATE To travel from one place to another regularly in search of a plentiful food supply or good breeding grounds. MONOCULAR VISION The area seen by one eye only, rather than by both eyes working together. MOULTING Shedding worn-out feathers and growing new ones in their place. NECTAR The sweet liquid produced by a flower to attract birds and insects to feed from the flower and so pollinate it. NESTLING A baby bird that is still in the nest and cannot fly. NOCTURNAL Active by night. SEABIRD Birds that spend most of their time over the open sea and only come ashore to breed. SECONDARY FEATHERS One of the inner wing feathers. SPECIES A group of birds of the same type that can breed with one another and live in the same area. SPECULUM A white or coloured patch that some ducks have across the inner wing feathers. STOOP To swoop down (bird of prey). TALONS The sharp, curved claws of a bird of prey. TERRITORY An area occupied by a bird that it may defend against other birds of the same species. TERTIALS A bird’s innermost flight feathers, which shape the wing to the body to ensure a smooth flight. THERMAL A rising column of warm air, often at the edge of a cliff or hillside, on which soaring birds glide. VERTEBRATE Any animal that has a backbone. Birds are vertebrates. WILDFOWL A wide range of mostly web- footed birds found in, on, or near water, such as ducks, geese and swans. Flight feather Hide at a bird reserve Pellets Seabird in flight Red-breasted goose preening its feathers