Long life: I passed a death sentence on two ducklings

My collection of poultry here in Northamptonshire (consisting at present of six ducks and eight hens) includes two little chattering call ducks named Boris and Marina. I called the drake Boris after the Mayor of London, and its partner Marina after the Mayor’s wife. The poultryman who sold them to me said that call ducks were so devoted to each other that if one of them died the other would inevitably die soon afterwards.