Relict species
A species which is thought to have been more widespread in the past but now, usually because of climatic change, has a discontinuous breeding distribution. For example, the Ring Ouzel Turdus toquatus is a relict species in southern Europe, where it is confined to high mountains, whereas further north it is more widespread. Presumably it was more generally distributed in the south during the cool period after the Ice Age, but as the climate became warmer it faced increasing competition from northward spreading species like its close relative the Blackbird T. merula, and was gradually forced out of the southern lowlands.From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver