However, if paired before the arrival, the female will keep watch at the site entrance while the male continues digging. While finishing up the nest, the male puts on a show for the females. Bank swallows are socially monogamous. Males are attracted to heavier females. The clutch size averages between 2 to 7 eggs, with only one brood per year.
Males take over when females leave the nest.
Incubation periods range from 13 to 15 days. There is rapid growth in the first 6 to 8 days, escpeially with the tarsi. The tarsal development enables them to stand straight. The young leave the nest between 8 to 22 days. The adults reduce their feeding and use vocalization to encourage the young to leave.