Beverly Mills Gyllenhaal

When you upload a bird photo to the terrific Facebook group called “What’s This Bird?” you tend to get an identification back in a matter of seconds.

A few nights ago, however, something was wrong.

I like to count how long it takes for my mystery bird to be pegged, and it’s rare that even five seconds tick by before several veteran birders on the Facebook site from the American Bird Association agree on the species.

Here’s the bird that kept everyone guessing.

But this time I had uploaded a photo of a small, greenish-gray bird – drab except for white bars on its wings. I knew from my guidebook that this bird was a type of Flycatcher, but which one?

East of the Mississippi River this time of year, the guidebook showed eight very similar possibilities: The Yellow-bellied, Acadian, Willow, Alder and Least Flycatchers, all in the Empidonax species group called “Empids;” or else the Olive-sided Flycatcher, Eastern Phoebe or Eastern Wood-pewee.

Although my Flycatcher was on a branch close to the ground obscured by green leaves in low light, I had no doubt Facebook’s crackerjack birders would solve the riddle.

And so I began to count – 10, 20, 30 seconds – then a whole minute. That’s odd, I thought. Was everybody on vacation?

After about five very slow minutes, I saw the Facebook signal that someone started typing. And it turns out that identifying Flycatchers is so difficult that the ensuing deliberation sounded like a bunch of scientists judging a dog show.

“My gut says Eastern Wood-Pewee,” the first person wrote. “Any Empidonax would have a cleaner chest, but this bird has a smudgy gray “vest.” Definitely not a Phoebe — a Phoebe would have a black face contrasting the paler grey back, also a brighter white lower belly.”

Hooray, I thought. Mystery solved. And then someone else started typing:

“The relatively short primaries suggest otherwise. A Pewee would have very long primaries. Also a Pewee would have a much less pronounced eye ring. Empids can have a smudgy vest. This is an Acadian Flycatcher.”

The back and forth went on for a couple of days, and even some of the best birders in Washington, D.C., got involved.

Here are three views of the bird that turned out to be an Acadian Flycatcher.

The front view doesn't give you much information.

The light colored beak, brown head coloring and whitish breast were all clues.

With the next comment, we generally settled on the Acadian:

“I will add my vote for Acadian Flycatcher,” wrote one of the most respected and thorough contributors. “The yellow underside of the bill, the moderately long primary extensions and the location all point to Acadian Flycatcher. Right now in southern Maryland, Acadians and their little two-note calls are everywhere!”

For me, one of the most compelling parts of birding is the detective work that goes into figuring out what we’ve seen. These days, we’re armed with dozens of books, apps, websites and laminated pamphlets to help with identifications.

Acadian Flycatcher view of pronounced wing bars.

In my early days of birding, anything beyond the most common species presented a challenge. Anders took photos of almost every bird, and we’d collect the mystery birds at the end of the day. Then we, too, would eagerly compare tail feathers, eye rings and beaks – just like the experts — to try and figure out the IDs. Oftentimes it’s a lot harder than you’d think.

My Flycatcher adventure was a reminder that the complexity of the avian world is enormous. There’s always more to learn. It turns out that the best way to figure out which Flycatcher you’re looking at is to catch their song. Without it, you may never be sure. If I’d known that the two-note call of the Acadian Flycatcher sounds like pizza (piz-ZAH), I wouldn’t have needed Facebook.

A bird’s “vocalizations” are definitive — way more reliable than its smudgy vest or belly color. (However, the process of learning hundreds of combinations of peeps, buzzes, squawks and trills is daunting. A story for another day.)

So what did I learn from my first Acadian Flycatcher? Sometimes, even the best birders get stumped.

One friend had some advice when it came to Flycatchers. “If it doesn’t vocalize, then just move along,’’ he said. “Pretend you didn’t see it.’’

Be sure to try out “What’s this Bird? when you’re stumped. It’s usually fast and easy. Meanwhile, here’s a gallery of various Flycatchers. Scroll over the phots for IDs.

Great Crested Flycatcher

Eastern Wood-Pewee

Vermillion Flycatcher

Eastern Kingbird, in the Flycatcher family

Acadian Flycatcher, star of our post