“Russet-backed” vs. “Olive-backed” Swainson’s Thrushes

Over the past decade, the work of Kristen Ruegg and her colleagues has shown that the two forms of Swainson’s Thrush not only look different, but migrate on different schedules to markedly different wintering grounds. They hybridize in a contact zone in British Columbia, but that contact zone is quite narrow, prompting occasional rumors and rumblings of a potential future species split. One of the proposed lines of evidence concerns differences in vocalizations. [Read more]

More on the Mystery Empid Call

A few months ago I wrote about a mysterious new “whit-beert” call that I took to be a previously undescribed sound of Yellow-bellied Flycatcher. Now, new information has come to light that calls my earlier conclusions into question. [Read more]

Greater vs. Lesser Yellowlegs

Can you tell Greater and Lesser Yellowlegs apart by voice? Can anybody? [Read more]

The “Tink” Call

Many species of warbler and sparrow give high, sharp “tink” notes that seem worth of their own category, separate from the “call” and the “flight call.” [Read more]

Learning Laplands

In trying to catalog Lapland Longspur calls, I ended up making a map of variation. [Read more]

North by Northwest

There are few species in North America as ambiguous as Northwestern Crow (Corvus caurinus). Even in a group of birds that are exceedingly similar the differences between American Crow (Corvus brachyrhynchos) and Northwestern Crow are minuscule at best. The only “surefire” way to tell them apart is by range; however a number of sources also cite vocal differences as a distinguishing characteristic. [Read more]

The Dawn Song of Brown Creeper

If you had asked me six months ago whether Brown Creeper had a distinctive dawn song, I would have told you no. But as a matter of fact, it does. [Read more]

Video Library: Large Gulls

The internet is full of wild bird videos. If you want to learn about the behavior and vocalizations, it can be a great place to start, at least for certain species. Gulls are a terrific example. [Read more]

What Gulls Say

Gull enthusiasts are weird. They hang out at landfills. They go to the beach when it’s freezing cold, or just to see what’s in the parking lot. They’ll stare at a single bird for hours, puzzling over insanely minute details. When it comes to identifying a mystery gull, they look at everything; they ignore nothing. Except vocalizations. [Read more]

The “Two-part Calls” of Empidonax

As far as I know, three species of Empids give these calls. In one species, the two-part call is familiar enough to be mentioned in field guides, at least. The two-part call of the second species is described only in the scientific literature. And that of the third is, as far as I know, being described in this blog post for the first time. [Read more]