nesting

The nesting instinct is proper to birds.

a pair of swans nesting by the river

The swallows are nesting in the woodshed.

a dozen geese homing to their summer nesting grounds.

As a schoolboy with a avid interest in birds, David Wingate was present in 1951 when a Bermudan naturalist succeeded in weaseling the first cahow out of its deep nesting crevice.

Above that terrible nesting-place of gloom the stories of the mute houses were lividly outlined;at the very top, the chimneys stood palely out.

In software engineering, the degree of complication of a system or system component, determined by such factors as the number and intricacy of interfaces, the number and intricacy of conditional branches, the degree of nesting, the types of data structures, and other system characteristics.