Apparently 95% of female salty sparrow's mated with more than one partner.
According to Professor Chris Elphick from the University of Connecticut:
We found that nearly every clutch of eggs was the product of more than one father, and that within broods it was extremely common for any two siblings to have different fathers.
One in three nests had a different father for every chick, and the average brood of chicks had more than 2.5 fathers
The sparrows nest amongst the saltmarshes, and are vulnerable to frequent high tides, which can cause a high level of nest loss.
Very high tides occur every four weeks - the same length of time it takes for the sparrow to raise a family.
Proffesor Elphick believes that the mating strategy may be attempt to minimize the risk of the adverse conditions.