Spotted Lanternfly in the Lower Susquehanna River Watershed

Second Mountain Hawk Watch is located on a ridge top along the northern edge of the Fort Indiantown Gap Military Reservation and the southern edge of State Game Lands 211 in Lebanon County, Pennsylvania.  The valley on the north side of the ridge, also known as St. Anthony’s Wilderness, is drained to the Susquehanna by Stony Creek.  The valley to the south is drained toward the river by Indiantown Run, a tributary of Swatara Creek.

The hawk watch is able to operate at this prime location for observing the autumn migration of birds, butterflies, dragonflies, and bats through the courtesy of the Pennsylvania Game Commission and the Garrison Commander at Fort Indiantown Gap.  The Second Mountain Hawk Watch Association is a non-profit organization that staffs the count site daily throughout the season and reports data to the North American Hawk Watch Association (posted daily at hawkcount.org).

Today, Second Mountain Hawk Watch was populated by observers who enjoyed today’s break in the rainy weather with a visit to the lookout to see what birds might be on the move.  All were anxiously awaiting a big flight of Broad-winged Hawks, a forest-dwelling Neotropical species that often travels back to its wintering grounds in groups exceeding one hundred birds.  Each autumn, many inland hawk watches in the northeast experience at least one day in mid-September with a Broad-winged Hawk count exceeding 1,000 birds.  They are an early-season migrant and today’s southeast winds ahead of the remnants of Hurricane Florence (currently in the Carolinas) could push southwest-heading “Broad-wings” out of the Piedmont Province and into the Ridge and Valley Province for a pass by the Second Mountain lookout.

The flight turned out to be steady through the day with over three hundred Broad-winged Hawks sighted.  The largest group consisted of several dozen birds.  We would hope there are probably many more yet to come after the Florence rains pass through the northeast and out to sea by mid-week.  Also seen today were Bald Eagles, Ospreys, American Kestrels, and a migrating Red-headed Woodpecker.

Migrating Broad-winged Hawks circle on a thermal updraft above Second Mountain Hawk Watch to gain altitude before gliding away to the southwest.

Migrating insects included Monarch butterflies, and the three commonest species of migratory dragonflies: Wandering Glider, Black Saddlebags, and Common Green Darner.  The Common Green Darners swarmed the lookout by the dozens late in the afternoon and attracted a couple of American Kestrels, which had apparently set down from a day of migration.  American Kestrels and Broad-winged Hawks feed upon dragonflies and often migrate in tandem with them for at least a portion of their journey.

Still later, as the last of the Broad-winged Hawks descended from great heights and began passing by just above the trees looking for a place to settle down, a most unwelcome visitor arrived at the lookout.  It glided in from the St. Anthony’s Wilderness side of the ridge on showy crimson-red wings, then became nearly indiscernible from gray tree bark when it landed on a limb.  It was the dreaded and potentially invasive Spotted Lanternfly (Lycorma delicatula).  This large leafhopper is native to Asia and was first discovered in North America in the Oley Valley of eastern Berks County, Pennsylvania in 2014.  The larval stage is exceptionally damaging to cultivated grape and orchard crops.  It poses a threat to forest trees as well.  Despite efforts to contain the species through quarantine and other methods, it’s obviously spreading quickly.  Here on the Second Mountain lookout, we know that wind has a huge influence on the movement of birds and insects.  The east and southeast winds we’ve experienced for nearly a week may be carrying Spotted Lanternflies well out of their most recent range and into the forests of the Ridge and Valley Province.  We do know for certain that the Spotted Lanternfly has found its way into the Lower Susquehanna River Watershed.

This adult Spotted Lanternfly landed in a birch tree behind the observers at the Second Mountain Hawk Watch late this afternoon.  It was first recognized by its bright red wings as it glided from treetops on the north side of the lookout.

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