Black and Pigeon Guillemots

Black Guillemot in “hunch-whistle” posture, Moville, Ireland, 5/22/2007. Photo by Sean Mack (CC 2.0). Black Guillemot in “hunch-whistle” posture, Moville, Ireland, 5/22/2007. Photo by Sean Mack (CC 2.0). “No differences known,” says the Sibley guide about the voices of Black and Pigeon Guillemots. This isn’t quite true. But the differences certainly are not widely known. [Read more]

Ever heard of Pine Flycatcher?

The purpose of this blog post is to draw attention to one of the least known Empidonax species, one that has yet to appear in the ABA area, but is high on the list of many a birder as a potential vagrant. The bird I am speaking of is Pine Flycatcher (Empidonax affinis). An inhabitant of montane forests from just shy of the Arizona border to northern Central America, it favors (as one would expect) pine-dominated woodland. [Read more]

The Swifts of Mexiquillo

We were excited to arrive at Parque Natural Mexiquillo before the break of dawn in June, to look for waterfall-loving swifts. [Read more]

Mexico’s Mystery Owl

It’s not every day that you photograph and audio record a bird that has never been photographed or audio recorded before. [Read more]

How to Identify a Timberline Sparrow

On the field marks and audio cues that separate nominate Brewer’s Sparrows from the “Timberline” subspecies. [Read more]

Common vs. Chihuahuan Ravens

I’m starting to think that voice is actually a very good character — maybe the best field character — for separating these two species. [Read more]

A Bicknell’s Thrush Critique

In 1995, in the 40th Supplement to their checklist, the American Ornithologists’ Union recognized Bicknell’s Thrush (Catharus bicknelli) as a full species, splitting it from the Gray-cheeked Thrush (Catharus minimus) on the basis of “differences in morphology, vocalizations, habitat preferences, and migration patterns.” In this post, I reassess the evidence for a consistent difference in flight calls between Bicknell’s and Gray-cheeked Thrushes. [Read more]

Long Calls of Gulls

Most people don’t listen to gulls much. But as I’ve paid more attention to them over the past year, I’ve realized that many species can indeed be identified by sound alone, and this fact has greatly improved my birding skills. [Read more]

Common and Hoary Redpolls

Some have argued that Common and Hoary Redpolls differ in vocalizations. I set out to verify this claim. [Read more]

Empid Mystery Solved!

Remember the mysterious two-part call of the unidentified Empid? Nacho Areta has filled in the missing piece of the puzzle. [Read more]