Category: Western Flycatcher

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A Tricky Flycatcher To Identify

The tiny flycatchers of the genus Empidonax are notoriously difficult to identify by visual clues alone.  Determining the species by sight requires a good look under ideal conditions.  Even then, these birds are a tricky lot.  Don’t believe it?  Take a gander at these photos of an Empidonax flycatcher found atop Second Mountain in Lebanon County at sunrise this morning…

Yellow-bellied Flycatcher
One of the telltale signs of an Empidonax flycatcher from outside the group of eastern species is the presence of an expanded rear edge of a well-defined eye ring.
Yellow-bellied Flycatcher
Only the Pacific-slope and Cordilleran Flycatchers, groups currently lumped together by taxonomists as the Western Flycatcher, exhibit the teardrop-shaped eye ring.  In the lower Susquehanna region, Western Flycatchers have been recorded as vagrants during autumn and in early winter on several occasions, most recently along the river in Conoy Township, Lancaster County, in December of 2023.  (See post from December 20, 2023)
Yellow-bellied Flycatcher
For now, that 2023 record will remain the most recent.  With a turn of its head providing a better angle in direct sunlight, the apparent expansion of the rear portion of the eye ring turns out to be little more than a pale post-ocular feather on this bird.  The broad (but uniform) eye ring, rounded head, small bill, short tail, and the unbroken coloration of the underside areas all conspire to indicate that this is probably a Yellow-bellied Flycatcher (Empidonax flaviventris).  Disappointing?  Hardly.  Yellow-bellied Flycatchers are strictly migrants in the Lower Susquehanna River Watershed.  They are rarely seen as they pass through traveling to and from their breeding grounds in the moist coniferous forests, bogs, and swamps of the northernmost United States and southern Canada.  A Neotropical species, the Yellow-bellied Flycatcher winters in southern Mexico and Central America.
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Western Flycatcher on the Susquehanna

What was the attraction that prompted dozens of birders to hike more than a mile to a secluded field edge along the Northwest Lancaster County River Trail on this last full day of autumn?  It must be something good.

Birders photographing a rarity in the vicinity of the Shock's Mill Railroad Bridge along the Susquehanna in Lancaster County
Birders photographing a rarity in the vicinity of the Shock’s Mill Railroad Bridge along the Susquehanna in Conoy Township, Lancaster County, earlier today.

Indeed it was.  A Western Flycatcher (Empidonax difficilis), first discovered late last week, has weathered the coastal storm that in recent days pummeled the Lower Susquehanna River Watershed with several inches of rain and blustery winds.  Western Flycatchers nest in the Rocky Mountain and Pacific Coast regions of North America.  They spend their winters in Mexico.  There are several records of these tiny passerines in our area during December.  The first, a bird found in an area known as Tanglewood during the Southern Lancaster County Christmas Bird Count (CBC) on December 16, 1990, was well documented—photographs were taken and its call was tape recorded.  It constituted the first record of a member of the Western Flycatcher’s “Pacific-slope” subspecies group ever seen east of the Mississippi River.  It was reported through December 26, 1990.  The Tanglewood flycatcher and a bird sighted years later on a subsequent “Solanco CBC” were both found inhabiting wooded thickets in the shelter of a ravine created by one of the Susquehanna’s small tributaries.

Western Flycatcher along Northwest Lancaster County River Trail
Early this morning, a vagrant Western Flycatcher finds a sunny spot adjacent to the Northwest Lancaster County River Trail to search the vines, shrubs, and tree limbs for spiders and small insects.
Western Flycatcher along Northwest Lancaster County River Trail
The diminutive Western Flycatcher on the lookout for flying insects from an elevated perch in the treetops.
Western Flycatcher along Northwest Lancaster County River Trail
Like other Western Flycatchers which have been found during the month of December in Lancaster County, this individual has some topographic protection from cold northwest winds.  It spends its time in a thicket along the edge of woodlands on the leeward side of the railroad grade that rises as the approach to the nearby Shock’s Mill Bridge.

How long will this wandering rarity remain along the river trail?  For added sustenance, sunny days throughout the coming winter offer ever-increasing chances of stonefly hatches on the adjacent river, particularly in the vicinity of the stone bridge piers.  But ultimately, the severity of the weather and the bird’s response to it will determine its destiny.

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