But hope springs eternal. Like many animal species including man, redwinged blackbirds are sexually dimorphic, which means that the males and females look different. Though there are no differences at the time they hatch, from that moment on male redwings grow faster and for a longer period of time than their female siblings. Perhaps as a result, their feathers grow more slowly and they learn to perch later than females. In the adults, differences in plumage, size and coloration are well known.
Males are shiny black with bright red epaulets.
The smaller females are a cryptic, striped brown. Some females also carry the red epaulets more commonly ascribed to male redwings, Clark said. Because of their different maturation rates, Clark is also looking at the evolutionary cost of last-born male babies, which almost certainly extend the nests' exposure to predators, she said. A youngest male further delays when all can fledge. How parents accommodate the differing needs of their individual young is also a subject of Clark's research, as is the question of the evolutionary cost of males feeding one or more nests in their polygenous territories.