Rose-breasted Grosbeak – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

September 27, 2025

Late May Action in the Forest

Here’s a short preview of some of the finds you can expect during an outing in the Lower Susquehanna River Watershed’s forests this week…

The Mountain Laurel, designated as Pennsylvania’s state flower, is now in bloom.

Mountain Laurel Flower Buds — The buds of the Mountain Laurel remind us of a sugary frosting freshly squeezed from a baker’s pastry bag.

Mountain Laurel Flowers — The flowers of the Mountain Laurel, an evergreen understory shrub, invite pollinators to stop by for a sweet treat.

Little Wood-Satyrs (Megisto cymela) are patrolling forest edges looking for mates and, to host their eggs and larvae, the stands of grasses they find most suitable.

Many of the species of small butterflies we call skippers are now active. The Zabulon Skipper can be found patrolling grassy forest edges, particularly near streams, ponds, and wetlands.

Among the showiest of our butterflies, the Red-spotted Purple (Limenitis arthemis astyanax) is seen here on the leaves of a Black Cherry, its favored host plant.

Butterfly observers will do well to pay a visit to the new Susquehanna Riverlands State Park on Furnace Road north of Hellam in York County, Pennsylvania.

Trail to Schull's Rock Overlook — Upon arrival at Susquehanna Riverlands, drive back the gravel road for about a mile to the parking area at the edge of the agricultural field. Then, hike the trail through the woods and farm hedgerow to the Schull’s Rock overlook on the river. In the forests along this route, the understory is dominated by colonial stands of Common Pawpaw trees.

Along the lookout trail to Schull’s Rock, the Common Pawpaws’ large leaves help them to shade out potentially fast-growing competition. In proper growing situations, pawpaws develop clonal suckers that mature over time to create colonial stands of a single genetic plant.

Common Pawpaw understory. — A Common Pawpaw understory along the approach to Schull’s Rock.

During our recent visit to Schull’s Rock, dozens of Zebra Swallowtails were seen along the trail, many in the vicinity of their sole host plant, the Common Pawpaw. But even more were observed along the edges of the fields and woods where nectar sources like this Multiflora Rose were being visited by numbers of butterflies we normally see only among abundant species like Cabbage Whites. Absolutely amazing!

Scull's Rock Overlook — And the view of the Susquehanna and the Shock’s Mills railroad bridge at the mouth of Codorus Creek is pretty good too!

Common Pawpaw and Hooded Warbler — You can look for colonial stands of Common Pawpaw at other parks and preserves along the lower Susquehanna as well. Birds like this Hooded Warbler can sometimes be found among them in mature riparian forests along the steep slopes of the river gorge.

Common Pawpaw and Baltimore Oriole — A Baltimore Oriole in a Common Pawpaw along a forest edge.

Meanwhile in the treetops, the spring thrust of Neotropical migrants is drawing to a close. The Blackpoll Warbler is typically one of the last to transit the lower Susquehanna valley on its way to northern coniferous forests for summer. They’ve had an unusually protracted movement through the region this spring, the earliest individuals reported during late April. Though very difficult to see in the canopy of the mature trees where it feeds and sings, hearing one is often a benchmark for senior birders each spring. Older observers have often said of the Blackpoll Warbler’s high-pitched song, a rapid series of insect-like staccato “tseet” notes, that it was the first they could no longer detect as their ears started losing sensitivity.

In many tracts along the lower Susquehanna this spring, the American Redstart is turning out to be the most common nesting warbler. Conditions favoring their reproductive success in recent cycles, as well as good survival rates during their migrations and stays on wintering grounds, have filled many lowland forests with redstart songs in 2025. Is this the start of a trend or just an exceptionally good year? Time will tell.

Yet one more reason for a stroll in local forests this week is the chance to see and hear the Rose-breasted Grosbeak. Look for these Neotropical relatives of the cardinal nesting on territories in mature stands of deciduous trees like this Yellow Poplar, a species also known as the Tuliptree.

They spend nearly all their time among the canopy foliage of the largest timber…

September 5, 2024September 30, 2024

This Week’s Review of the Morning Fallouts

Clear, cool nights have provided ideal flight conditions for nocturnal Neotropical migrants and other southbound birds throughout the week. Fix yourself a drink and a little snack, then sit down and enjoy this set of photographs that includes just some of the species we found during sunrise feeding frenzies atop several of the Lower Susquehanna River Watershed’s ridges. Hurry up, because here they come…

The Blackburnian Warbler was another plentiful species.

Cape May Warblers have an affinity for conifers like this Eastern White Pine.

But when traveling in mixed flocks with other migrants, Cape May Warblers can also be found feeding in the crown foliage of deciduous trees.

This adult Tennessee Warbler appears to be adorned in a very worn set of plumage…

Like the Tennessee Warbler, the Nashville Warbler was common among mixed flocks.

This Chestnut-sided Warbler was one of several found among the more common species of migrants.

A Black-and-white Warbler uses its nuthatch-like feeding behavior to search the tree bark for edible invertebrates.

To see the Common Yellowthroat, one must cease looking upward into the high canopy and instead give the aching neck a rest by peering into the low vegetation at the forest edge.

While checking the low growth, keep an eye open for other migrants among the shrubs and tangles. This Magnolia Warbler glows in the rays of a rising sun as it searches for a meal after a long night of travel.

Here we found a perky little House Wren.

Back in the middle and upper reaches of the trees, we find what has been by far the most numerous of the flycatchers seen during our visits to fallout sunrises. Eastern Wood-Pewees are appearing in very good numbers and can be seen quarreling and battling for hunting perches from which they are ambushing flying insects.

The numbers of migrating Least Flycatchers and other members of the genus Empidonax may be reaching their seasonal peak this week.

Scarlet Tanagers are currently a common find following nocturnal flights.

A Scarlet Tanager peers down from the top of a Red Maple.

Swainson's Thrush — The Neotropical thrushes are beginning to move south now as well. We found this newly arrived Swainson’s Thrush at Rocky Ridge County Park in York County during sunrise this morning.

Not surprisingly, the Red-eyed Vireo is one of the most numerous of the migrants seen feeding in the deciduous canopy following a nocturnal flight event. It’s not at all unusual to see dozens filing the trees around a ridgetop overlook or along a forest edge. Be certain to check these congregations carefully, especially the groups of birds feeding in the lower branches of tall timber or in the tops of smaller trees. This week we found…

…several hungry Yellow-throated Vireos arriving after nocturnal flights,…

…and a Philadelphia Vireo (Vireo philadelphicus) at the hawkwatch at Rocky Ridge County Park in York County.

Though not a Neotropical migrant, the easier-heard-than-seen Red-breasted Nuthatch is beginning to wander south into the lower Susquehanna region. Most of these birds will eventually continue on to the pine forests of the southern United States for winter, but a few could remain to become seasonal visitors at feeding stations.

Ruby-throated Hummingbirds are on the move; their migration to the tropics is well underway and nearing its peak. Ruby-throats are diurnal migrants that do a majority of their flying during the hours of daylight. The notable exception: the nighttime portion of the long southbound flight some of the birds make to cross the Gulf of Mexico.

The Red-headed Woodpecker is another diurnal migrant. This denizen of temperate climates is currently beginning to move to its wintering grounds, an area that extends from the latitudes of the lower Susquehanna south to the Gulf of Mexico and central Texas.

Juvenile Red-headed Woodpecker — A juvenile Red-headed Woodpecker during a brief pit stop.

The flights of roving bands of masked Cedar Waxwings continue. Their numbers appear to be an improvement over those of 2023.

At regional hawk-counting stations, observers are seeing more Broad-winged Hawks and other species beginning to move through.

"Kettling" Broad-winged Hawks — The frequency of Broad-winged Hawks passing the lookouts one at a time is giving way to the occurrence of larger and larger “kettling” groups that search out thermal updrafts to save energy while migrating. By mid-September each of these “kettles” can include one hundred birds or more. On the peak days, the daily Broad-winged Hawk totals can reach one thousand or more.

The migration is by no means over; it has only just begun. So plan to visit a local hawkwatch or other suitable ridgetop in coming weeks. Arrive early (between 7 and 8 AM) to catch a glimpse of a nocturnal migrant fallout, then stay through the day to see the hundreds, maybe even thousands, of Broad-winged Hawks and other diurnal raptors that will pass by. It’s an experience you won’t forget.

Broad-winged Hawk Gliding Away to the Southwest — A Broad-winged Hawk gliding away to the southwest.

Be certain to click the “Birds” tab at the top of this page for a photo guide to the species you’re likely to see passing south through the lower Susquehanna valley in coming months. And don’t forget to click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab to find a hawk-counting station near you.

More birds are on the way. Here’s a look at this evening’s liftoff of nocturnal migrants detected by National Weather Service Radar in State College, Pennsylvania. (NOAA/National Weather Service Doppler Radar image)

September 6, 2023September 7, 2023

Surf’s Up: The Waves Keep Rolling In

“Waves” of warblers and other Neotropical songbirds continue to roll along the ridgetops of southern Pennsylvania. The majority of these migrants are headed to wintering habitat in the tropics after departing breeding grounds in the forests of southern Canada. At Second Mountain Hawk Watch, today’s early morning flight kicked off at sunrise, then slowed considerably by 8:30 A.M. E.D.T. Once again, in excess of 400 warblers were found moving through the trees and working their way southwest along the spine of the ridge. Each of the 12 species seen yesterday were observed today as well. In addition, there was a Northern Parula and a Canada Warbler. Today’s flight was dominated by Bay-breasted, Blackburnian, Black-throated Green, and Tennessee Warblers.

A Blackburnian Warbler at sunrise on Second Mountain.

A hungry Blackburnian Warbler feeding on insects.

Black-throated Green Warbler on Second Mountain. — Black-throated Green Warblers were a plentiful species among both yesterday’s and today’s waves of Neotropical migrants.

A juvenile Black-throated Green Warbler on Second Mountain — A juvenile Black-throated Green Warbler.

Tennessee Warbler on Second Mountain. — One of the scores of Tennessee Warblers seen on Second Mountain early this morning.

A male Black-throated Blue Warbler on Second Mountain. — A male Black-throated Blue Warbler.

Magnolia Warbler on Second Mountain. — Compared to yesterday’s flight, lesser numbers of Magnolia Warblers were seen today.

An adult male Wilson's Warbler on Second Mounatin. — An adult male Wilson’s Warbler was a good find among the hundreds of birds swarming the ridgetop.

Other interesting Neotropical migrants joined the “waves” of warblers…

This Warbling Vireo was found peering from the cover of the shady forest.

A minimum of six Rose-breasted Grosbeaks were identified including the juvenile male seen here in first-fall plumage. Other good sightings were Scarlet Tanagers, an adult male Baltimore Oriole, and a dozen or more Ruby-throated Hummingbirds.

Least Flycatcher on second Mountain. — Three Least Flycatchers were heard calling and seen chasing one another through a stand of dead timber on the south slope below the lookout.

September 15, 2022September 15, 2022

Something in the Air Tonight

There’s something in the air tonight—and it’s more than just a cool comfortable breeze.

It’s a major nocturnal movement of southbound Neotropical birds. At daybreak, expect a fallout of migrants, particularly songbirds, in forests and thickets throughout the region. Warblers, vireos, flycatchers, thrushes, Scarlet Tanagers, and Rose-breasted Grosbeaks pass through in mid-September each year, so be on the lookout!

May 15, 2020August 14, 2023

The Layover

After nearly a full week of record-breaking cold, including two nights with a widespread freeze, warm weather has returned. Today, for the first time this year, the temperature was above eighty degrees Fahrenheit throughout the lower Susquehanna region. Not only can the growing season now resume, but the northward movement of Neotropical birds can again take flight—much to our delight.

A rainy day on Friday, May 8, preceded the arrival of a cold arctic air mass in the eastern United States. It initiated a sustained layover for many migrating birds.

Bobolinks (Dolichonyx oryzivorus) in flocks of as many as fifty birds gathered in weedy meadows and alfalfa fields for the week.

A Bobolink sheltering in a field of Sweet Vernal Grass (Anthoxanthum odoratum) during the rain on Friday, May 8th.

Two of seven Solitary Sandpipers (Tringa solitaria) in a wet field on Friday, May 8. Not-so-solitary after all.

Grounded by inclement weather, Rose-breasted Grosbeaks (Pheucticus ludovicianus) made visits to suburban bird feeders in the lower Susquehanna valley. (Charles A. Fox image)

Freeze warnings were issued for five of the next six mornings. The nocturnal flights of migrating birds, most of them consisting of Neotropical species by now, appeared to be impacted. Even on clear moonlit nights, these birds wisely remained grounded. Unlike the more hardy species that moved north during the preceding weeks, Neotropical birds rely heavily on insects as a food source. For them, burning excessive energy by flying through cold air into areas that may be void of food upon arrival could be a death sentence. So they wait.