When bird mating goes wrong

OLDER readers will remember the notorious Ne Temere decree, which discouraged Catholics from marrying outside the fold. Such unions are acceptable nowadays but a ‘matrimonia mixta’ in Virginia, Co Cavan, is raising eyebrows.

A mute swan and a goose have taken to living as husband and wife on the local river. Swans have a reputation for virtue and decorum, so how odd is this union?

There are seven swan species worldwide. When kept together in ornamental collections, such as those of the Wildfowl and Wetlands Trust in Britain, swans mate occasionally with members of the ‘wrong’ species. They may do so even when suitable partners of their own kind are available. Liaisons between mutes and five of the other swan species have been documented. Only the black-necked swan of South America seems to have an unblemished record. The offspring of such unions are generally sterile but some may be fertile.