Glossary

Altricial

See nidicolous.

Amber List Species

When a species' breeding population or range has declined by 25 to 50% in the last 25 years, has recovered from a historical decline, is a rare breeder, or is of either European or international importance, it is placed on the amber list of Birds of Conservation Concern. The list was revised in 2002 by a number of conservation organisations.

Anatomy

Parts of the bird have specific names that can help in identifying birds. See diagrams.

Charts

The charts show the maximum number of any one species visiting the garden at any one time in a particular week. This method of counting is used in the Garden Birdwatch survey.

Eclipse

Eclipse plumage describes the plumage of drake wild fowl in the autumn when they have shed their wing feathers. The usual spectacularly bright plumage would put them at risk from predators, so they moult to a drabber plumage (similar to the female) which offers better camouflage and more protection.

Fledging

The time when a chick is getting its first set of proper feathers.

Fledgling

A young bird that has learnt to fly. This is often mistakenly used to mean a nestling, but many birds learn to fly while still dependent on their parents.

Green List

The species that appear on the green list are not considered to be of conservation concern.

High BTO Alert

A High BTO Alert is issued for birds that have seriously declined in numbers. For example perhaps because of the loss of habitat, or other possibly unknown reasons. See also red list species. The list was compiled in 1999.

Hirundine

This is a bird species of the hirundinidae family and is often used by birders to describe mixed groups of Swallows and martins. Swifts are not hirundines.

Immature

An immature bird is a juvenile that has undergone its first moult but does not yet have full adult plumage.

Incubation Period

The period is the time between the egg being laid and the nestling hatching.

Juvenile

A young bird that is no longer dependent on its parents but has not gained its adult plumage.

Medium BTO Alert

A Medium BTO Alert is issued for birds that have declined in numbers, but not seriously enough to warrant a High BTO Alert, or that have started to recover from a period when the populations was endangered. See also amber list species. The list was compiled in 1999.

Monogamy

The practice of having only one mate at a time. See also Polygamy

Nestling

A nestling is generally a bird that is either too young and frail to leave the nest or is still dependent on its parents. There are two types of nestling: nidifugous and nidicolous. See fledgling.

Nestling Period

The time from hatching to becoming a juvenile.

Nidicolous

A nidicolous (or altricial) nestling is naked, blind and helpless after it hatches. Most songbirds, woodpeckers and pigeons are nidicolous, for example, Blackbirds. See Eggs and Nestlings.

Nidifugous

A nidifugous (or precocial) nestling is down covered and active shortly after hatching and can leave the nest if necessary. Most game birds, ducks and geese are nidifugous, for example a Mallard chick.  See Eggs and Nestlings.

Polyandrogyny

A form of polygamy and the practice of both males and females having more than one mate at a time.

Polyandry

A form of polygamy and the practice of having more than one male mate at a time. See also Polygyny.

Polygamy

The practice of having more than one mate at a time. See Monogamy.

Polygyny

A form of polygamy and the practice of having more than one female mate at a time. See Polyandry.

Precocial

See nidifugous.

Primaries

The main flight feathers along the outer part of the edge of the wing. See topography.

Red List Species

When a species' breeding population or range has declined by more than 50% in the last 25 years, is not recovering from a historical decline, or is globally threatened species, it is placed on the red list of Birds of Conservation Concern. The list was revised in 2002 by a number of conservation organisations. N.B. Not all High BTO Alert species appear on the red list, though they are probably candidates.

Secondaries

The shorter flight feathers along the inner part of the edge of the wing. See topography.

Speculum

The speculum is a patch formed by colourful or iridescent secondary feathers on the wings of ducks, such as Mallard and Teal.