Black-capped Chickadee Invasion

Our cute lovable chickadees are resident birds, remaining in the same general area throughout the year, often throughout their lives.  In the Mid-Atlantic States, there are two species.  The tiny Carolina Chickadee is at the northern limit of its geographic range in the Piedmont Province of southcentral Pennsylvania.  The slightly larger Black-capped Chickadee is a year-round resident mostly to the north of the Lower Susquehanna River Watershed.  Within the Susquehanna basin, an intergrade zone of the two species occurs in the mountains and bottomlands of the southern portion of the Ridge and Valley Province just to the north of the Pennsylvania cities of Carlisle, Harrisburg, and Lebanon.  The range of the Carolina Chickadee, as well as the hybrid zone, has gradually crept north during the last fifty years—as much as twenty or thirty miles—while the range of the pure-bred Black-capped Chickadee has simultaneously withdrawn almost entirely from the lower Susquehanna, particularly in the valleys.

Every few years, presumably when their numbers are too great for the sustenance available from the wild food crop in their home range, Black-capped Chickadees invade the more southerly range of both Carolina Chickadees and the hybrids in the intergrade zone.  This appears to be one of those years.  Black-capped Chickadees are working their way south and showing up at feeding stations stocked with sunflower seeds, safflower seeds, and/or peanuts—sometimes in flocks numbering five to ten birds or more.

Let’s take a closer look at the two species…

In the Lower Susquehanna River Watershed, the Carolina Chickadee is the resident species from the Great Valley (Cumberland/Lebanon Valley) south into Maryland.
In the Lower Susquehanna River Watershed from the Great Valley (Cumberland/Lebanon Valley) south into Maryland, the Carolina Chickadee is the resident species of “tit”.
The Black-capped Chickadee is slightly larger than the Carolina Chickadee.
The Black-capped Chickadee, usually a resident of highlands to the north of the lower Susquehanna valley, is slightly larger than the Carolina Chickadee. The most conspicuous difference is the extensive amount of white in the “black-cap’s” wings, both on the edges of the flight feathers and on the set of coverts at the “shoulder”.  Black-capped Chickadees often appear longer tailed and bigger headed than Carolina Chickadees and the edge of the black bib is often more ragged.  The buffy wash on the flanks is usually more noticeable on the Black-capped Chickadee than on a Carolina.  Hybrids from the intergrade zone, having a varying blend of characteristics, are more difficult to identify.

Not only is now a good time to carefully check the chickadees you see, but it’s an opportune time to watch for other invaders from the north, specifically the “winter fiches” including Pine Siskins, Evening Grosbeaks, Purple Finches, Red Crossbills (Loxia curvirostra), and White-winged Crossbills (Loxia leucoptera).  During recent weeks, each of these species has been reported by observers at hawk-counting stations on local ridgetops, an indication that they too are experiencing inadequate food resources in their home ranges.

So, as winter approaches, you’ll want to keep an eye on those feeders—and don’t forget to keep an ear on the pines and hemlocks.  The rewards could be many!

White-winged Crossbills during an invasion of the lower Susquehanna region in February 2009. 
White-winged Crossbills during an invasion of the lower Susquehanna region in February 2009.  Previously unnoticed in the shade, the sounds of their bills crunching the cones led to the discovery of this female (left) and male (right) among a small flock of six crossbills found feeding on Eastern Hemlock seeds at ground level.

Migrating Golden Eagles

Why would otherwise sensible people perch themselves atop a rocky outcrop on a Pennsylvania mountaintop for ten hours on a windy bone-numbing bitter cold and sometimes snowy November day?  To watch migrating raptors of course.

November is the time when big hawks and eagles migrate through and into the lower Susquehanna valley.  And big birds rely on big wind to create updrafts and an easy ride along the region’s many ridges.  The most observable flights often accompany the arrival of cold air surging across the Appalachian Mountains from the northwest.  These conditions can propel season-high numbers of several of the largest species of raptors past hawk-counting sites.

Observers brave howling winds on the Waggoner’s Gap lookout to census migrating late-season raptors.

Earlier this week, two windy days followed the passage of a cold front to usher-in spectacular hawk and eagle flights at the the Waggoner’s Gap Hawk Watch station on Blue Mountain north of Carlisle, Pennsylvania.  Steady 30 M.P.H. winds from the northwest on Monday, November 2, gusted to 50 M.P.H. at times.  Early that morning, two Rough-legged Hawks, rarities at eastern hawk watches, were seen.  They and two American Goshawks (Astur atricapillus) provided a preview of the memorable sightings to come.  Two dozen Golden Eagles migrated past the lookout that day.  Then on November 3, thirty Golden Eagles were tallied, despite west winds at speeds not exceeding half those of the day before.

Here are some of the late-season raptors seen by hardy observers at Waggoner’s Gap on Monday and Tuesday, November 2 & 3.

In November, Red-tailed Hawks are the most common migratory raptor counted at hawk watch stations in the Susquehanna region.
 A juvenile American Goshawk passes the Waggoner's Gap lookout.
An uncommon bird, a juvenile American Goshawk, passes the Waggoner’s Gap lookout.
An adult Golden Eagle circles on an updraft along the north face of Blue Mountain to gain altitude before continuing on its journey.
The plumage of juvenile and immature Golden Eagles often creates a sensation among crowds at a lookout.  Golden Eagles don’t attain a full set of adult feathers until their sixth year.  This individual is probably a juvenile, also known as a hatch-year or first-year bird.  At most, it could be in its second year.  Click the “Golden Eagle Aging Chart” tab on this page to learn more about these uncommon migrants and their molt sequences as they mature.
The gilded head feathers of a Golden Eagle glisten in the afternoon sun.
An adult Golden Eagle passing Waggoner’s Gap.  The population known as “Eastern Golden Eagles” winters in the Appalachian Mountains and, with increasing frequency, on the Piedmont and Atlantic Coastal Plain Provinces of the eastern United States, where it often subsists as a scavenger.
Another first-year (juvenile) or second-year Golden Eagle.
A local Red-tailed Hawk (top left) trying to bully a migrating Golden Eagle.  A dangerous business indeed.
Through December, Bald Eagles, presently the more common of our eagle species, are regular migrants at Waggoner’s Gap and other Susquehanna valley hawk watch sites.
Red-shouldered Hawks are reliable early November migrants.
An adult Red-shouldered Hawk from above.
And an adult Red-shouldered Hawk from below.
Though their numbers peak in early October, Sharp-shinned Hawks, particularly adults like this one, continue to be seen through early November.
A Northern Harrier on the glide path overhead.
Merlins, like other falcons, are more apt to be seen in late September and October, but a few trickle through in November.

While visiting a hawk watch, one will certainly have the opportunity to see other birds too.

Common Ravens are fascinating birds and regular visitors to the airspace around hawk watches.  Most are residents, but there appears to be some seasonal movement, particularly among younger birds.
Most people think of Common Loons as birds of northern lakes.  But loons spend their winters in the ocean surf, and to get there they fly in loose flocks over the Lower Susquehanna River Watershed each spring and fall.  They are regularly seen by observers at hawk watches.
Like ducks, geese, and swans, migrating Double-crested Cormorants assemble into aerodynamic V-shaped flocks to conserve energy.
Pine Siskins continue their invasion from the north.  Dozens of small flocks numbering 10 to 20 birds each continue to be seen and/or heard daily at Waggoner’s Gap.  A flock of Evening Grosbeaks (Coccothraustes vesperitinus), another irruptive species of “winter finch”, was seen there on November 3.

As a finale of sorts, near the close of the day on November 3, two Golden Eagles sailed past the north side of the Waggoner’s Gap lookout, one possessing what appeared to be a tracking transmitter on its back.  An effort was commenced by the official count staff to report the sighting to the entity monitoring the bird—to track down the tracker, so to speak.

A Golden Eagle with a backpack transmitter passing Waggoner’s Gap Hawk Watch at 3:39 P.M. Eastern Standard Time on November 3, 2020.

To see the count reports from Waggoner’s Gap and other hawk watches throughout North America, be certain to visit hawkcount.org