Bicknell's Thrush — Wings of NH

What you notice first

The song at dusk from inside the krummholz — a thin, spiralling, flute-like phrase that rises at the end, more nasal and more upward than a Swainson's or a Hermit.

Voice

A buzzy, downslurred "beer" call and the ethereal, rising, ventriloquial song, given mostly in the half hour after sunset and again before dawn.

Where & when

The dense, wind-stunted balsam fir at the top of the White Mountains — the Presidentials, Franconia Ridge, Mount Moosilauke, and a handful of other high summits. Access means a long uphill hike to be in place at dusk in June or early July.

Why it's hard

Range edge and a tiny footprint. New Hampshire is near the southern limit of a global range that's essentially six Northeastern states and Atlantic Canada; the bird only uses a sliver of habitat above 3,000 feet, sings for barely an hour a day, and stays hidden inside the shrubs while doing it.

One of the last North American songbirds to be described — split from the Gray-cheeked Thrush in 1995 — and one of the most range-restricted. The entire world population breeds in the montane fir of the Northeast and winters, as far as anyone can tell, mostly on the island of Hispaniola, which means the bird is squeezed by habitat loss at both ends of a very long flight.

In the field it is a hard call. It looks like a dull Gray-cheeked or a cold-toned Hermit Thrush; the reliable separation is elevation, habitat, voice, and a warm rufous cast to the tail contrasting a greyer back.

Females mate with several males and the males all help feed the resulting broods, an arrangement thought to be a response to the harsh, unpredictable mountaintop climate. Cold summer, and a nest can fail outright.