You know how you'll sometimes be walking down the street and you'll observe one pigeon following another one around, fluffing up his feathers and trying to look attractive? That's not some annoying dude pursuing an uninterested female. According to biologist Elizabeth Carlen, those are two lovers in a committed relationship. 

"They constantly do their mating dance," she said. "That's one way they keep up their pair bond."

Carlen works in a lab at Fordham University, where she's pursuing a Ph.D. She's studying the birds, which — fun Valentine's Day fact —mate for life. "Pigeons are one of the few wildlife New Yorkers interact with on a daily basis," she said. "They are this connection we have to nature."

They're romantic, they're ubiquitous — and they have crazy visual abilities. According to a 2015 study, a group of pigeons was taught to read mammograms. And after a couple of weeks, they could successfully distinguish between benign and malignant cells 85 percent of the time. (That's not all they can do: Quoting past research, the study says pigeons have also demonstrated they can discern "misshapen pharmaceutical capsules...letters of the alphabet...basic object categories such as cats, flowers, cars, and chairs...identities and emotional expressions of human faces...and even paintings by Monet vs. Picasso, among many other impressive feats.")

Pigeons were brought here from Europe in the 1600s and have settled in nicely, having found an unending supply of food in the garbage, and what Carlen refers to as people who engage in "mercy feeding." Unlike the average New Yorker, they like the local real estate. "New York City buildings are perfect," said Carlen. "They mimic the cliffs of the native regions where these pigeons are found." 

(They also get drafted to participate in local art projects.) 

And while the birds often get a bad rap, New Yorkers cared enough to bring 3,000 of them into the Wild Bird Fund last year to be rehabilitated. Rita McMahon, co-founder and director of the center, says what she often hears from rescuers is "I looked at that bird, it looked at me and I had to help it."