breeding ground

a place where animals breed or to which they return to breed.

an environment suitable for or fostering the development of an idea, thing, etc.: a breeding ground for violence.

Origin of breeding ground

First recorded in 1930–35

Mr. Belloc once said, very wisely and truly, that inertia was the breeding-ground of inspiration.

Hugh |Arthur Christopher Benson
What has he ever done, in all his dull days, to make that harmless mind a breeding-ground for every sort of degenerate idea?

Witching Hill |E. W. Hornung
The scarlet-legged oyster-catcher, or “sea-pie,” makes Annet its breeding-ground; as also do many of the terns.

The Isles of Scilly |Jessie Mothersole
All the land was a breeding-ground for the dividends of Hedworth Westerling.

The Last Shot |Frederick Palmer

There can be therefore no doubt that the north of Scotland is within the extreme southern limit of its breeding-ground.

British Birds in their Haunts |Rev. C. A. Johns