They either lay their eggs in the nest thus appropriated, or oddly enough build one for themselves on the top of it.

They usually sit on their own eggs and rear their own young; but Mr.

Hudson says it is probable that they are occasionally parasitic, for he has seen the young of this species following old birds of a distinct kind and clamouring to be fed by them.

The parasitic habits of another species of Molothrus, the M.

bonariensis, are much more highly developed than those of the last, but are still far from perfect.