It begins on a sunny morning in spring each year, just as the ground temperature reaches sixty degrees or more…
Eastern Subterranean Termites emerge in unison from a nest located in the soil beneath a log. Each of these swarming “alates” is a potential king or queen seeking to find a location with an ample supply of fallen timber to provide food for establishment of a new colony. They are escorted to the surface by a soldier (lower center) equipped with powerful jaws for protecting the existing nest. Similar-looking worker termites tend the nest, the queen, her eggs, and their siblings, but usually remain hidden from view. The workers feed upon wood, hosting cellulose-digesting protozoa and bacteria in their guts to break down the fibers. This symbiotic relationship is an important mode of decomposition in the forest, the process that turns wood into the organic matter that enriches soil and helps it to retain more moisture.Termites are among the numerous arthropods that join fungi and a variety of microbes to decompose dead wood and other plant matter into the nutrients and organic materials used by living plants to thrive and grow.Within moments of emerging, swarming “alates” ascend a tree trunk or other vertical surface from which they can take flight.Eastern Subterranean Termite “alates” gather atop a stump before launching skyward.Termites swarm in massive numbers in an attempt to overwhelm the predators that are inevitably attracted to their sudden appearance. The few “alates” that survive to find a source of rotting wood in which to begin a new colony are the only hope for continuing their king and queen’s legacy.Soon after lift off, the majority of swarming termites are consumed by swallows, swifts, and other birds, but some are discovered at ground level.A lightning-fast strike with its tongue and this Green frog has snatched up yet another termite. Those that slip by the dragnet of terrestrial and aerial predators can sometimes start a new colony in the ground beneath a dead tree or in a vulnerable house or other wooden structure. To keep a small clan from invading your home, be certain the wood elements of your building(s) are kept dry and are not in contact with dirt, soil, bark mulch, etc. Regular inspections for evidence of their presence can head off the long-term damage termites can inflict on the stuff we construct with tree skeletons.A Green Frog wearing its breakfast. Its next chance for a termite feast may come during the autumn when the Drywood Termites (Kalotermitidae) swarm.
Of course, termites aren’t the only groups of insects to swarm. As heated runoff from slow-moving thundershowers has increased stream temperatures during the past couple of weeks, there have occurred a number of seasonal mayfly “hatches” on the Susquehanna and its tributaries. These “hatches” are actually the nuptial flights of newly emerged imago and adult mayflies. The most conspicuous of these is the Great Brown Drake.
Seen here with a much smaller and more typical regional mayfly to its left, the Great Brown Drake was for several years infamous for swarming the lights and creating traffic hazards on bridges spanning the Susquehanna. During the past two weeks, nighttime flights of these giants have ventured out to gather at well lit locations in housing and business districts more than a dozen miles from the river. Earlier this century, this proclivity to wander probably led the Great Brown Drake to first invade silty segments of the Susquehanna as a colonizer from its native range in the Mississippi watershed.
Swarms of another storm-related visitor are being seen throughout the lower Susquehanna valley right now. Have you noticed the Wandering Gliders?
Throughout the month, swarms of Wandering Gliders, the most widespread dragonflies in the world, descended on areas hit by localized slow-moving thundershowers. Large numbers of these global travelers are known to get swept up within the thermal air masses that lead to these storms. In suitable terrain within the path of the downpours, they linger to search for flooded places where they can mate and deposit eggs. Wandering Gliders frequently mistake large parking lots at shopping malls, grocery stores, etc. for wetlands and will be seen in these areas depositing eggs upon the hoods and roofs of shiny motor vehicles, surfaces which appear puddle-like in their eyes.More dragonfly swarms are yet to come. Adult Common Green Darners are presently in the Lower Susquehanna River Watershed mating and depositing eggs within vegetated ponds, lakes, and wetlands. Beginning in August, adult Common Green Darners and other migratory species including Black Saddlebags, Carolina Saddlebags, Wandering Gliders, and Twelve-spotted Skimmers will begin swarming as they feed on flying insects (including lots of mosquitos and gnats) and start working their way toward the Atlantic Coastal Plain. Along the barrier islands by September, concentrations of southbound dragonflies can reach the thousands, particularly at choke points like Cape May, New Jersey, and Cape Charles, Virginia. So be sure to keep an eye on the sky for swarms of dragonflies during coming weeks. And don’t forget to check out our “Damselflies and Dragonflies” page by clicking the tab at the top of this page.
Can it be that time already? Most Neotropical birds have passed through the Lower Susquehanna River Watershed on their way south and the hardier species that will spend our winter in the more temperate climes of the eastern United States are beginning to arrive.
Here’s a gallery of sightings from recent days…
During the past two weeks, thousands of Broad-winged Hawks, including this adult bird, crossed the skies of the lower Susquehanna valley on their way to Central and South America for our winter.A juvenile Broad-winged Hawk passes into the sunset during its first autumn migration.Blackpoll Warblers are among the last of the Neotropical species to transit the region. They’ll continue to be seen locally through at least early October.Blue-headed Vireos are the October vireo during the fall, the other species having already continued toward tropical forests for a winter vacation.The lower Susquehanna region lies just on the northern edge of the wintering range of the Blue-gray Gnatcatcher, a species found nesting locally among treetops in deciduous woods. Look for their numbers to swell in coming days as birds from further north begin rolling through the region on their way south.Sharp-shinned Hawks delight visitors at ridgetop hawk watches during breezy late-September and early-October days. They allow closer observation than high-flying Broad-winged Hawks due to their habit of cruising just above the treetops while migrating.A Sharp-shinned Hawk glides over a lookout.Late September/early October is falcon time at area hawk-counting stations, the Peregrine Falcon often being the most anticipated species.Pale “Tundra Peregrines”, a subspecies that nests in the arctic, are strictly migratory birds in the Mid-Atlantic States. They are presently passing through on their way to South America. Like Neotropical songbirds, their long flights provide them with the luxury of never experiencing a winter season.This Carolina Saddlebags and other migratory dragonflies, which normally leave the area by mid-September, are still lingering in the lower Susquehanna region, much to the pleasure of the falcons that feed upon them.An male American Kestrel in pursuit of dragonflies found swarming around the lookout at Second Mountain Hawk Watch in Lebanon County, Pennsylvania.A male American Kestrel stooping on a dragonfly.Osprey will be among the birds of prey passing hawk watch sites during the coming two weeks. The first week of October often provides the best opportunity for seeing the maximum variety of raptors at a given site. On a good day, a dozen species are possible.Seeing cinnamon-colored juvenile Northern Harriers is symbolic of the October migration flights.Bald Eagles always thrill the crowd.In addition to raptors, resident Common Ravens are regularly sighted by observers at hawk watches and elsewhere during the fall season.Hawk-counting stations sometimes log movements of Red-bellied Woodpeckers during late September and early October. This species has extended its range into the Lower Susquehanna River Watershed only during the past one hundred years, making these seasonal migration movements a recent local phenomenon.Blue Jays are currently on the move with breeding birds from the forests of Canada and the northern United States moving south. Hundreds can be seen passing a given observation point during an ideal morning.Blue Jays find a pile of peanuts to be an irresistible treat. Provide the unsalted variety and watch the show!
Be sure to click on these tabs at the top of this page to find image guides to help you identify the dragonflies, birds, and raptors you see in the Lower Susquehanna River Watershed…
Damselflies and Dragonflies
Birds of Conewago Falls
Hawkwatcher’s Helper: Identifying Bald Eagles and other Raptors
During the coming two weeks, peak numbers of migrating Neotropical birds will be passing through the northeastern United States including the lower Susquehanna valley. Hawk watches are staffed and observers are awaiting big flights of Broad-winged Hawks—hoping to see a thousand birds or more in a single day.
During its passage through the Lower Susquehanna River Watershed, an adult Broad-winged Hawk sails over Second Mountain Hawk Watch in Lebanon County, Pennsylvania.A hatch-year/juvenile Broad-winged Hawk gazes toward hawk watchers on the ground.
Broad-winged hawks feed on rodents, amphibians, and a variety of large insects while on their breeding grounds in the forests of the northern United States and Canada. They depart early, journeying to wintering areas in Central and South America before frost robs them of a reliable food supply.
The Carolina Saddlebags (Tramea carolina), this one photographed at Second Mountain Hawk Watch on September 8th, is the rarest of the lower Susquehanna region’s migratory dragonflies. Autumn Broad-winged Hawk movements coincide with southbound flights of the Carolina Saddlebags and the more numerous migratory dragonfly species: Common Green Darner, Wandering Glider, Twelve-spotted Skimmer, and Black Saddlebags. “Broad-wings” will often eat these and other dragonflies during migration and can sometimes be seen catching and feeding upon them while still soaring high overhead.
While migrating, Broad-winged Hawks climb to great altitudes on thermal updrafts and are notoriously difficult to see from ground level. Bright sunny skies with no clouds to serve as a backdrop further complicate a hawk counter’s ability to spot passing birds. Throughout the Lower Susquehanna River Watershed, the coming week promises to be especially challenging for those trying to observe and census the passage of high-flying Broad-winged Hawks. The forecast of hot and humid weather is not so unusual, but the addition of smoke from fires in the western states promises to intensify the haze and create an especially irritating glare for those searching the skies for raptors.
Smoke from fires along the California coast and in central Utah can be seen streaming east this morning. (NOAA/GOES image)Smoke from western fires and humid air creates a band of haze in Ohio, Pennsylvania, New Jersey, and states to the south this morning. (NOAA/GOES image)
A migrating Broad-winged Hawk in the glare of a hazy sky. In addition to visibility problems, swarms of Spotted Lanternflies above the treetops make distant hawks difficult to discern for hawk watchers scanning the horizon with binoculars.
It may seem gloomy for the mid-September flights in 2021, but hawk watchers are hardy types. They know that the birds won’t wait. So if you want to see migrating “Broad-wings” and other species, you’ve got to get out there and look up while they’re passing through.
Migrating Ospreys typically fly low enough and are large enough to be spotted even during the haziest of conditions.Bald Eagles like this fourth-year bird can ascend to great altitude, but their size usually prevents them from sneaking past a lookout unnoticed.Peregrines escape notice not due to hazy sky conditions, but because they pass by so quickly. They’re being seen at local hawk watches now through October.
These hawk watches in the Lower Susquehanna River Watershed are currently staffed by official counters and all welcome visitors:
Rocky Ridge County Park Hawk Watch—3699 Deininger Road off Mount Zion Road (Route 24) northeast of York, Pennsylvania.
Second Mountain Hawk Watch—off Cold Spring Road on the grounds of Fort Indiantown Gap in Lebanon County, Pennsylvania.
Waggoner’s Gap Hawk Watch—where Route 74 crosses Blue Mountain north of Carlisle, Pennsylvania.
—or you can just keep an eye on the sky from wherever you happen to be. And don’t forget to check the trees and shrubs because warbler numbers are peaking too! During recent days…
Northern Parula at Chiques Rock County Park in Lancaster County.Black-and-white Warbler at Rocky Ridge County Park in York County.Cape May Warbler at Chiques Rock County Park in Lancaster County.Bay-breasted Warbler at Rocky Ridge County Park in York County.
