Courtesy National Park Service.
This is not news to songbirds, who started mixing crooning and wooing long before Frank Sinatra lamented that he "didn't stand a ghost of a chance with you."
Songbirds perform their vocal gymnastics to mark territory and get noticed by eligible females. Many scientists think the quality of the song tells her about his health -- since only a healthy guy bird could belt out the avian equivalent of "Lover Man."
Now we hear that female black-capped chickadees do more than listen closely. When their fellas lose out in a song competition, the ladies respond.
But not with a soothing, "Honey, maybe you can't hit high C-sharp, but you're still number-one. Come kiss my chicken lips."
No. The takeaway message for the ladies is: "I married a loser!"
And then they step outside the nest for some quick action with another guy! In evolutionary terms, that would guarantee that at least some of her young get top-notch genes.
The day I lost my baby
He calls it eavesdropping, since the females overhear the "conversations" of others.
Mennill studied wild-living black-capped chickadees at the Queen's University biological station and identified high- and low-status males. As with people, upper-crust chickadees skim off the cream, so to speak. "At a food source... everybody makes way for the highest ranking bird," he says.
Sing me softly of the blues
In contrast, a submissive song uses a different pitch, giving the first songster some breathing room..
During mating season, Mennill hung out in the woods with a laptop and a speaker. He gathered the birds by playing the familiar chickadee call.
The genetics told the sordid tale, Mennill says. "After a high-ranking guy lost a competition because I matched and overlapped his song, his female engaged in extrapair copulations." To Mennill, this proves that the females are eavesdropping on the guy-to-guy discussion.
Although songbirds were once considered monogamous -- they hang out in couples, and all of the young in the nest of a dominant male are normally his -- their behavior actually has elements of Beach Blanket Bingo. Many females do a certain amount of stepping out on their mates.
So when the lady heard her guy humiliated by the computerized song, about half of her future young wound up having a different dad, Mennill reports. "She's accustomed to hearing him win every song contest, but after hearing him lose, she changes her reproductive strategy."
It's a lot stranger in the night
The overlapping and matching songs may have other uses, says Mennill. "Most animals, including chickadees, live in groups, where many males are singing at the same time. You have to have capacity to address one individual if you want to say 'Hey you, I want you out of my territory.'"
Moral of the story: Guys, if you want to impress the ladies, tune up those vocal cords,.
-- David Tenenbaum
Female Eavesdropping on Male song Contests in Songbirds, Daniel Mennill et al, Science, 3 May 2002.