“It’s a competitive process,” said Pierre Comizzoli, a research veterinarian at the National Zoo. “We always believe that all animals reproduce. It’s not true. For example, some males are going to be dominant.”
In some animal species — elephants, primates, deer — one extra tasty male may, um, fall in love with numerous females, leaving other males out of luck.
“In respect to these songbirds we have in our backyard, the female is the chooser and the male is the displayed,” said ornithologist Bruce Beehler, a research associate at the National Museum of Natural History. “He’s the one that does the best that he can. He gets the nest ready. He sings. He gets a patch of territory. It’s up to the female to decide who’s the sexiest or has the best nest or the best song.”
And the ones who are second, third or fourth best?
“I wouldn’t be surprised if close to half of the males out in the environment of the typical songbird do not reproduce in an average year,” Beehler said. “It’s rough and tumble”. It looks on paper very tidy, and when it works, it works great, mainly for the female.”
Most successful songbirds will have already produced one brood so far this year, back in the spring.
“The ones that are really jung ho try to have a second brood,” Beehler said. “They get one set of babies out, send them on their way, then try again. That’s what evolution is all about: getting out of those offspring, as many as possible.”
That’s hard for male songbirds that aren’t able to carve out a bit of space to call their own.
“Birds that don’t even get territories, they’re called floaters,” Beehler said. “They’re sort of hanging around, hoping to find a little niche where they can establish themselves.”
Maybe that’s what I’m seeing: a floater. Or a young bird that hasn’t learned the ropes yet.
Male wrens build two or three nests in hopes of gaining a female’s approval.
“Females are attracted based on the location of the nest or how he’s constructed it,” Beehler said. “House wrens are also wonderful singers, one of my absolute favorites. So song is probably important to the female as well.”
“These birds don’t live a long time,” Beehler said. “With age comes experience. Practice makes perfect. The youngest birds — or ones coming back for the first time to reproduce — they’re going to be the ones not having success.”
For some species, there’s another complication: The places to mingle are too spread out.
“That’s the problem we have in the wild: The density of the animals is too low,” Comizzoli said. “And actually they cannot meet. If they do not meet, well, they cannot reproduce. That’s kind of unfortunate. This situation is really a consequence of human activity like deforestation or destruction or the fragmentation of the natural habitat.”
When you have a low density of individuals, it’s like living in a small town: The pickin’s are slim. And no one likes to settle.
“Even if they can see each other, maybe they’re not going to like each other,” Comizzoli said.
Scientists at places like the National Zoo try to help, introducing animals to one another in captive situations. Of course, that doesn’t guarantee chemistry, especially with some critters.
“Chetah females are extremely picky,” Comizzoli said. “They’re not going to breed with just any males. They’re going to be choosing their partners. If you don’t have enough males in your collection, and for some reason the females don’t like any males, well, they’re not going to reproduce.”
For some animals — giant pandas spring to mind — that leaves artificial insemination as the best option.
Right now we’re at the peak of summer. That wren is still dutifully trilling his love song. I asked Beehler if the bird would give up eventually, stop singing, take up a hobby for the rest of the summer like fantasy baseball or investing in NFTs.
“He probably won’t,” Beehler said. “He probably will go until the weather tells him it’s time to go south. He’ll pack his bags and think, ‘That was a crappy summer. Here’s hoping next spring is better.”’”
Maybe what that bird needs is a wingman.