Harems, murder, deceit and espionage, all in your yard: Springtime with the birds
A cast of avian characters roams area yards, set for the rising curtain of spring. Among them are bullies, cheats, and heroic single moms, murderous terrorists, warriors, and spies.
As breeding season nears, action abounds. Plots thicken.
Among most bird species, males show aggression. They sing to mark territory, attract mates, and warn competition. When bullies test the limits, bad things happen. For instance, competing male goldfinches easily come to blows, going at it beak and toenail, battling to the ground until one retreats or worse. The bully doesn't necessarily win.
Or consider the cheats. Male red-winged blackbirds maintain a harem, keeping vigil and marking territorial boundaries by song. Females, however, occasionally slip out and rendezvous with an especially alluring neighbor.
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Cheat though she may, in reality strengthening the gene pool, her harem's kingpin likely doesn't notice. After all, he's keeping eye on an entire entourage, and she's sly.
Some heroic single moms, though, show a single-minded devotion to home and family. Ruby-throated hummingbird moms, for instance, get no help from males, even the one with which she mates. Instead, she builds her nest, lays eggs, incubates them, feeds nestlings, and fledges them entirely alone.
Unfortunately, a few terrorists work their evil deeds in the secrecy of nest cavities. House sparrows, non-native birds whose numbers have exploded, compete for cavities with native birds, including bluebirds. When a house sparrow deems a given cavity should be his, he will attack the bluebird on the nest, kill her, and construct his nest atop her carcass. That's about as murderous as an avian species can get.
Oh, I know, hawks murder, too. But let's be honest: A hawk kills to eat or feed young. A house sparrow kills to get its way in the housing market. Pure evil.
Certain birds go to war without being murderous. I've watched a miniscule blue-gray gnatcatcher repeatedly dive-bomb and peck a nesting red-shouldered hawk, carrying out a days-long barrage in a battle intended to drive the hawk from the territory. While the hawk finds the little warrior not much more annoying than we might find a mosquito, the gnatcatcher aims to protect its territory, nest, eggs, and babes. It soldiers on.
The biggest spies in the avian world could do the CIA proud. A female brown-headed cowbird knows everything happening in the neighborhood. She wears camouflage gray and, from a lofty perch, spies on nesters, sneaking about until she catches a female leaving its nest. Then zip! She slips in, lays her egg, and is gone before the host discovers the trespass.
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When the cowbird carries out her dirty act of espionage, she's confident that because her eggs hatch more quickly than other birds' eggs, her baby crowds out the host's. So a surrogate mom raises the cowbird kids to maturity while the cowbird continues spying on other nests, laying more eggs.
Fortunately, at least one model family guy adds a sense of goodness to balance the rottenness. A male bluebird loyally presents his mate with nice, juicy caterpillars while she incubates their eggs. He takes a few shifts on the nest to give her time to stretch. And he feeds the nestlings with the same tender care as she does − a sweet twist to some otherwise dirty plots.
Watch for the drama in your yard!
For more information about birds and bird habitat, see Sharon Sorenson's books How Birds Behave, Birds in the Yard Month by Month, and Planting Native to Attract Birds to Your Yard. Follow daily bird activity on Facebook at SharonSorensonBirdLady, or email her at chshsoren@gmail.com.
This article originally appeared on Evansville Courier & Press: What are the birds doing in my yard this spring?
