A sexual population is a set of organisms in which any pair of members can breed together.

Nests are often solitary, although a few pairs may breed relatively close together at good locations.

Other breeding season records, however, indicate that between five and 10 pairs probably breed in most years.

Until 1939 up to 12, but more usually about seven, pairs bred along the 15 miles of chalk cliffs.

Five to 25 days after fledglings leave the nest, the pair may breed again.

Clown Would not a pair of these have bred, sir?

You can even let newly-established pairs breed in the community tank at the outset.

In particular, groups form a clear dominance hierarchy where only dominant pairs breed.

Even though the pair had bred many times (once to the point of suspending shows) the two never produced any live offspring.

A second pair was also present, but did not breed.