Most birds are monogamous, in that they pair bond for a season, or at least for one round of babies. And some birds mate for life. Red-winged blackbirds, on the other hand, are one of the most polygamous avian species out there. One male can have up to 15 mates every year.
Juggling all these lady friends is hard work. Every day during breeding and egg-laying season, March to May, males patrol their home ranges—sometimes as large as two NHL hockey rinks. They visit each baby mama for about two minutes every hour. Careful if you’re bird watching in their turf: males and females are both very aggressive. They’ll go after intruding birds as large as sandhill cranes, and sometimes, unfortunate joggers and hikers. Watch your hair!
Females nest in marshy areas, using wet, stringy vegetation—willow bark, cattail leaves—to weave a large cup, then lining it with mud and dry grass. They can lay multiple clutches of eggs per breeding season, producing a lot of half-siblings. Since each female can have several partners, sometimes even the offspring from one clutch of eggs have different fathers.