It’s dawn in the peat bog. A male red-winged blackbird, epaulets flashing, belts his conk-la-ree! from a cattail. He owns this marsh—or so he believes. Three females nest within his territory. He guards them with obsessive flights, chasing rival males. He is, by every measure, a success.
By J. S. Moraine
Consider the superb fairy-wren. The male has brilliant blue plumage—but females leave his territory to mate with males in other groups. Why? Two reasons. First, . A clutch of eggs with mixed paternity reduces the chance of inbreeding or inheriting two copies of a bad gene. Second, sperm competition . By mating with multiple males, females force sperm to race. The winner’s offspring may inherit faster, more competitive sperm themselves. breeding season cheats
So the next time you hear a male blackbird singing his heart out from a cattail, remember: he’s not just singing to attract a mate. He’s singing to keep his neighbor’s sperm out of his nest. And somewhere in the reeds, a small, dull-colored male is listening—waiting for his nine-second window. It’s dawn in the peat bog
