A Towering American Elm

During the past week, Uncle Tyler Dyer has been out searching for autumn leaves to add to his collection.  One of the species he had not encountered in previous outings was the American Elm (Ulmus americana), so he made a special trip to see a rare mammoth specimen in a small neighborhood park (Park Place) along Chestnut Street between 5th and Quince Streets in Lebanon, Pennsylvania.

American Elm at Park Place in Lebanon, Pennsylvania
Possibly the largest and oldest remaining American Elm in the lower Susquehanna watershed, the Park Place tree in Lebanon exceeds 60 feet in height and may be more than 300 years of age.  In the nearly one hundred years since Dutch elm disease (DED) first began killing elms in eastern North America, this tree has been spared the fatal effects of the infection.  DED is caused by several species of microfungi (Ophiostoma ulmi, O. himal-ulmi, and O. novo-ulmi) spread by numerous bark beetle (Curculionidae) species.  As early as 1928, infected beetles arrived in the United States from the Netherlands among shipments of logs.
Leaves of the American Elm.
Leaves of the American Elm.

There’s still time to get out and see autumn foliage.  With warmer weather upon us—at least temporarily—it’s a good time to go for a stroll.  Who knows, you might find some spectacular leaves like these collected by Uncle Ty earlier this week.  All were found adorning native plants!

Winged Sumac
Winged Sumac (Rhus copallina), a small native tree.  In case you’re wondering, it’s not poisonous.
Black Chokeberry
Black Chokeberry (Photinia melanocarpa), a native shrub also known as Aronia.  It produces black-colored fruits in summer.
Red-osier Dogwood
Red-osier Dogwood (Cornus sericea), a shrub that prefers wet or damp soils.  It yields white fruits.
Maple-leafed Viburnum
Maple-leafed Viburnum (Viburnum acerifolium), a native shrub of upland forest understories.
Highbush Blueberry
Highbush Blueberry (Vaccinium corymbosum), a native shrub and the source of many cultivated forms of the popular fruit.
To identify your finds, be certain to click the “Trees, Shrubs, and Woody Vines” tab at the top of this page to check out Uncle Ty’s extensive collection.

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…

Black-throated Green Warbler
A Black-throated Green Warbler.
Black-throated Green Warbler
The Black-throated Green Warbler was perhaps the most frequently identified treetop warbler during the most recent four mornings.
Black-throated Green Warbler
A Black-throated Green Warbler with a unique variation in the crown plumage.
Blackburnian Warbler
The Blackburnian Warbler was another plentiful species.
Cape May Warblers
Cape May Warblers have an affinity for conifers like this Eastern White Pine.
Cape May Warbler
But when traveling in mixed flocks with other migrants, Cape May Warblers can also be found feeding in the crown foliage of deciduous trees.
Tennessee Warbler
This adult Tennessee Warbler appears to be adorned in a very worn set of plumage…
Tennessee Warbler
…and its traveling companion looks like it’s overdue for a new set of feathers as well.
Nashville Warbler
Like the Tennessee Warbler, the Nashville Warbler was common among mixed flocks.
Nashville Warbler
A Nashville Warbler atop a Black Cherry.
Chestnut-sided Warbler
This Chestnut-sided Warbler was one of several found among the more common species of migrants.
Chestnut-sided Warbler
A Chestnut-sided Warbler.
Chestnut-sided Warbler
We were lucky enough to spot this male Chestnut-sided Warbler sporting his namesake flank feathers.
 Black-and-white Warbler
A Black-and-white Warbler uses its nuthatch-like feeding behavior to search the tree bark for edible invertebrates.
Common Yellowthroat
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.
Magnolia Warbler
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.
House Wren
Here we found a perky little House Wren.
Eastern Wood-Pewee
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.
 Eastern Wood-Pewee
An Eastern Wood-Pewee fiercely defending its hunting perch.
Eastern Wood-Pewee
An Eastern Wood-Pewee.
Least Flycatcher
The numbers of migrating Least Flycatchers and other members of the genus Empidonax may be reaching their seasonal peak this week.
Scarlet Tanagers
Scarlet Tanagers are currently a common find following nocturnal flights.
Scarlet Tanager
A Scarlet Tanager peers down from the top of a Red Maple.
Rose-breasted Grosbeak
Did you hear a loud squeak in the treetops?  It could be a southbound Rose-breasted Grosbeak stopping by for the day.
Rose-breasted Grosbeak
A Rose-breasted Grosbeak in a dead tree snag.
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.
Red-eyed Vireo
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…
Yellow-throated Vireo
…several hungry Yellow-throated Vireos arriving after nocturnal flights,…
Philadelphia Vireo
…and a Philadelphia Vireo (Vireo philadelphicus) at the hawkwatch at Rocky Ridge County Park in York County.
Red-breasted Nuthatch
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 Hummingbird
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.
Red-headed Woodpecker
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.
Cedar Waxwings
The flights of roving bands of masked Cedar Waxwings continue.  Their numbers appear to be an improvement over those of 2023.
Broad-winged Hawk
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.
Broad-winged Hawk
A Broad-winged Hawk soaring to gain lift from a thermal updraft above a hawkwatch lookout.

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)

Photo of the Day

Ninebark
The bright-red flower buds of the Ninebark (Physocarpus opulifolius) precede clusters of white blooms that will, in coming weeks, attract a variety of butterflies and other pollinators to this indigenous shrub.  Its peeling bark and colorful deciduous leaves attract interest throughout the year.  In the lower Susquehanna watershed, Ninebark is most frequently found growing along stream banks.  It will often thrive on steep slopes with moist soils, so is useful as an erosion control species as well.  To add it to your refuge’s landscape, look for it at nurseries that stock native plants.  Once there, you’ll find a variety of cultivars that are sure to satisfy even the fussiest of gardeners.

Arboreal Birds and Tent Caterpillars

During the past week, we’ve been exploring wooded slopes around the lower Susquehanna region in search of recently arrived Neotropical birds—particularly those migrants that are singing on breeding territories and will stay to nest.  Coincidentally, we noticed a good diversity of species in areas where tent caterpillar nests were apparent.

Eastern Tent Caterpillar Nest
The conspicuous nest of the Eastern Tent Caterpillar (Malacosoma americanum), a native species of moth.  The first instar of the larval caterpillars hatch in early spring from egg masses laid on the limbs of the host tree by an adult female moth during the previous spring.  Soon after they begin feeding on the host tree’s first tender shoots, these tiny, seldom-noticed larvae start communal construction of a silk tent to act as a shelter and greenhouse-like solar collector that will both provide protection from the elements and expedite their growth.
Eastern Tent Caterpillar
The familiar last instar of the Eastern Tent Caterpillar is the most consumptive stage of the animal’s life.  After feeding in the treetops, they will descend to the ground and seek a sheltered location to pupate.  Adult moths emerge in several weeks to take to the air, mate, and produce eggs to be deposited on a host tree for hatching next year.  The favorite host tree in forests of the Lower Susquehanna River Watershed: native Black Cherry.

Here’s a sample of the variety of Neotropical migrants we found in areas impacted by Eastern Tent Caterpillars.  All are arboreal insectivores, birds that feed among the foliage of trees and shrubs searching mostly for insects, their larvae, and their eggs.

Yellow-throated Vireo
The Yellow-throated Vireo nests, feeds, and spends the majority of its time feeding among canopy foliage.
Eastern Wood-Pewee
The Eastern Wood-Pewee is a flycatcher found in mature woodlands.  It feeds not only among the limbs and leaves, but is an aerial predator as well.
Northern Parula
The Northern Parula nests in mature forests along rivers and on mountainsides, particularly where mature trees are draped with thick vines.
Hooded Warbler
The Hooded Warbler (Setophaga citrina) is found among thick understory growth on forested slopes.
Ovenbird
The Ovenbird builds a domed, oven-like nest on the ground and forages in the canopy.
Kentucky Warbler
The Kentucky Warbler (Geothlypis formosa) nests in woodland undergrowth, often near steep, forested slopes.
Worm-eating Warbler
The Worm-eating Warbler (Helmitheros vermivorum) nests among woody understory growth on forested hillsides.
Scarlet Tanager
The Scarlet Tanager is often difficult to observe because of its affinity for the canopy of mature forest trees.

In the locations where these photographs were taken, ground-feeding birds, including those species that would normally be common in these habitats, were absent.  There were no Gray Catbirds, Carolina Wrens, American Robins or other thrushes seen or heard.  One might infer that the arboreal insectivorous birds chose to establish nesting territories where they did largely due to the presence of an abundance of tent caterpillars as a potential food source for their young.  That could very well be true—but consider timing.

Already Gone-  By the time Neotropical migrants arrive in our area, the larval stages of the Eastern Tent Caterpillar’s life cycle are already coming to an end.  The nests that these native insects constructed to capture the energy of the springtime sun have allowed the larvae to exit and browse foliage when conditions were suitable, then return for shelter when they were not.  While inside, the larvae could move among the chambers of their structure to find locations with a temperature that best suited their needs.  Therein the solar heating and communal warmth sped up digestion and growth.
Eastern Tent Caterpillar
Eastern Tent Caterpillar larvae are now in their bristly final-instar stage and the majority have already moved to the ground to each seek a place to pupate and metamorphose into an adult moth.  Arboreal Neotropical birds have scarcely had a chance to feed upon them, and ground-feeding species seem to lack any temptation.  As for the adult moths, they fly only at night and live for just one day, offering little in the way of food for aerial, arboreal, or ground-feeding birds.
Wild Turkey
Having left arboreal environs, Eastern Tent Caterpillar larvae are now food for ground-feeding birds like our resident Wild Turkeys.  They need only get past the bristly hairs on the caterpillar’s back and the foul taste that may result from its limited diet of cyanogenic Black Cherry leaves.
Yellow-billed Cuckoo
The arboreal Yellow-billed Cuckoo (seen here) and its close relative the Black-billed Cuckoo (Coccyzus erythropthalmus) are the two species of birds in our area known to regularly feed on bristly tent caterpillars.  But having just arrived from the tropics to nest, they’ll need to rely on other insects and their larvae as sources of food for their young.
Black Cherry defoliated by Eastern Tent Caterpillars.
Final-instar Eastern Tent Caterpillars often defoliate Black Cherry trees before moving to the ground to pupate. Their timing allows them to feed on the fresh foliage while it is still young and tender, and to largely avoid becoming food for the waves of Neotropical birds that arrive in the lower Susquehanna basin in May.

So why do we find this admirable variety of Neotropical bird species nesting in locations with tent caterpillars?  Perhaps it’s a matter of suitable topography, an appropriate variety of native trees and shrubs, and an attractive opening in the forest.

American Redstart
An American Redstart singing in a Black Cherry.  Unlike others in the vicinity, this tree nestled among several very large Eastern White Pines showed no signs of tent caterpillar activity.  It may be that for one reason or another, no adult female moth deposited her eggs on this particular tree.  During our visits, Black Cherry was but one of the diverse variety of native trees and shrubs found growing on the sloping topography that created attractive habitat for the nesting birds we found.  We happened to notice that a majority, but not all, of those Black Cherry trees were impacted by Eastern Tent Caterpillars.
Black Cherry in Flower
The end of the Eastern Tent Caterpillar’s larval surge may spell the end of their nests for the year, but it’s not the end for the Black Cherry and other host trees in the Prunus (cherry) and Malus (apple) genera.  Because it’s still early in the season, they have plenty of time to re-leaf and many will still flower and produce fruit.  Those flowers and foliage will attract numerous other insects (including pollinators) that benefit breeding birds.
Blue-winged Warbler
The Blue-winged Warbler inhabits shrubby breaks in the forest such as this utility right-of-way where Black Cherry trees have sprouted after their seeds arrived in waste deposited by fruit-eating (frugivorous) birds.  Already attractive to a variety of insectivores, these openings soon lure egg-laying Eastern Tent Caterpillar moths to the cherry trees growing therein.  Even in dense forest, a small clearing created by a cluster of dead trees makes good bird habitat and will sooner or later be visited by fruit-eating species that will inadvertently sow seeds of Black Cherry, starting yet another stand of host trees for Eastern Tent Caterpillars.  It’s the gap in the forest that often attracts the birds, some of which plant the host trees, which sometimes entice Eastern Tent Caterpillar moths to lay their eggs.
Red-Eyed Vireo
Adapt and Reuse-  A Red-eyed Vireo visits an Eastern Tent Caterpillar nest…
Red-eyed Vireo
…and ignores the few remaining occupants that could easily be seized to instead collect silk to reinforce its own nest.

Here in the Lower Susquehanna River Watershed, the presence of Eastern Tent Caterpillar nests can often be an indicator of a woodland opening, natural or man-made, that is being reforested by Black Cherry and other plants which improve the botanical richness of the site.  For numerous migratory Neotropical species seeking favorable places to nest and raise young, these regenerative areas and the forests surrounding them can be ideal habitat.  For us, they can be great places to see and hear colorful birds.

Scarlet Tanager
Our Lucky Break-  This Scarlet Tanager descended from the treetops to feed on spiders in a small forest clearing.

The Fog of a January Thaw

As week-old snow and ice slowly disappears from the Lower Susquehanna River Watershed landscape, we ventured out to see what might be lurking in the dense clouds of fog that for more than two days now have accompanied a mid-winter warm spell.

York Haven Dam Powerhouse
After freezing to a slushy consistency earlier this week, the Susquehanna is already beginning to thaw.   Below the York Haven Dam at Conewago Falls, the water is open and ice-free.
Mallards and a pair of American Wigeon on a frozen lake.
On frozen man-made lakes and ponds, geese and ducks like these Mallards and American Wigeon are presently concentrated around small pockets of open water.
American Robin in a Callery pear
During the past ten days, American Robin numbers have exploded throughout the lower Susquehanna valley.  The majority of these birds may be a mix of both those coming south to escape the late onset of wintry conditions to our north and those inching north into our region as early spring migrants.
American Robin
The January thaw has melted the snow from lawns and fields to provide thousands of visiting robins with a chance to forage for earthworms.
Cooper's Hawk
A visit by this young Cooper’s Hawk to the susquehannnawildlife.net headquarters garden sent songbirds scrambling…
Eastern Gray Squirrel
…but did nothing to unnerve our resident Eastern Gray Squirrels,…
Eastern Gray Squirrel
…which promptly went into tail-waving mode to advertise their presence.
Red-tailed Hawk
But earlier in the week, when heavy snow cover in the rural areas surrounding our urbanized neighborhood made it difficult for rodent-eating raptors to find food, we received brief visits from both a Red-tailed Hawk…
Red-shouldered Hawk
…and this young Red-shouldered Hawk, an uncommon bird of prey most often found in wet woods and other lowlands.
Eastern Gray Squirrel
To escape notice during visits by these larger raptors, our squirrels remained motionless and commenced performance of their best bump-on-a-log impressions.
Red-shouldered Hawk in flight.
Unimpressed, each of our visiting buteos remained for just a few minutes before moving on in search of more favorable hunting grounds and prey.
Early Successional Growth
As snow melted and exposed bare ground in fields of early successional growth, we encountered…
White-crowned Sparrow
…a flock of White-crowned Sparrows, most in first-winter plumage…
American Tree Sparrow
…and at least a dozen American Tree Sparrows.  During the twentieth century, these handsome songbirds were regular winter visitors to the lower Susquehanna region.  During recent decades, they’ve become increasingly more difficult to find.  Currently, moderate numbers appear to be arriving to escape harsher weather to our north.
Adult Male Northern Harrier
What could be more appropriate on a foggy, gray evening than finding a “gray ghost” (adult male Northern Harrier) patrolling the fields in search of mice and voles.

If scenes of a January thaw begin to awaken your hopes and aspirations for all things spring, then you’ll appreciate this pair of closing photographs…

Pileated Woodpecker in Silver Maple
The maroon-red flower buds of Silver Maples are beginning to swell.  And woodpeckers including Pileated Woodpeckers are beginning to drum, a timber-pounding behavior they use to establish breeding territories in habitats with suitable sites for cavity nesting.
Skunk Cabbage
In wet soil surrounding spring seeps and streams, Skunk Cabbage is rising through the leaf litter to herald the coming of a new season.  Spring must surely be just around the corner.

Birds of the Sunny Grasslands

With the earth at perihelion (its closest approach to the sun) and with our home star just 27 degrees above the horizon at midday, bright low-angle light offered the perfect opportunity for doing some wildlife photography today.  We visited a couple of grasslands managed by the Pennsylvania Game Commission to see what we could find…

Grasslands and Hedgerows
On this State Game Lands parcel, prescribed fire is used to maintain a mix of grasslands and brushy early successional growth.  In nearby areas, both controlled fire and mechanical cutting are used to remove invasive species from hedgerows and the understory of woodlots.  Fire tolerant native species then have an opportunity to recolonize the forest and improve wildlife habitat.  This management method also reduces the fuel load in areas with the potential for uncontrolled wildfires.
The sun-dried fruits of a Common Persimmon tree found growing in a hedgerow.
The sun-dried fruits of a native Common Persimmon tree found growing in a hedgerow.
Savanna-like Grasslands
Just one year ago, mechanical removal of invasive trees and shrubs (including Multiflora Rose) on this State Game Land was followed by a prescribed fire to create this savanna-like grassland.
Song Sparrow
Hundreds of Song Sparrows were found in the grasses and thickets at both locations.
White-throated Sparrow
White-throated Sparrows were also abundant, but prefer the tangles and shrubs of the thickets.
Northern Mockingbird
Northern Mockingbirds were vigilantly guarding winter supplies of berries in the woodlots and hedgerows.
Swamp Sparrow
In grasses and tangles on wetter ground, about a dozen Swamp Sparrows were discovered.
White-crowned Sparrow
The adult White-crowned Sparrow is always a welcome find.
White-crowned Sparrow
And seeing plenty of juvenile White-crowned Sparrows provides some assurance that there will be a steady stream of handsome adult birds arriving to spend the winter during the years to come.
Dark-eyed Junco
Dark-eyed Juncos were encountered only in the vicinity of trees and large shrubs.
Savannah Sparrow
Several Savannah Sparrows were observed.  Though they’re mostly found in treeless country, this particular one happened to pose atop a clump of shrubs located within, you guessed it, the new savanna-like grasslands.
Winter Wren
A tiny bird, even when compared to a sparrow, the Winter Wren often provides the observer with just a brief glimpse before darting away into the cover of a thicket.
Standing Clump of Timber
Within grasslands, scattered stands of live and dead timber can provide valuable habitat for many species of animals.
A "snag" with an excavated nest cavity.
Woodpeckers and other cavity-nesting birds rely upon an abundance of “snags” (standing dead trees) for breeding sites.
Red-bellied Woodpecker
This Red-bellied Woodpecker and about a dozen others were found in trees left standing in the project areas.
Yellow-bellied Sapsucker
A Yellow-bellied Sapsucker soaks up some sun.
Pileated Woodpecker
This very cooperative Pileated Woodpecker seemed to be preoccupied by insect activity on the sun-drenched bark of the trees.  This denizen of mature forests will oft times wander into open country where larger lumber is left intact.

Pileated Woodpecker

Northern Harrier
Just as things were really getting fun, some late afternoon clouds arrived to dim the already fading daylight.  Just then, this Northern Harrier made a couple of low passes in search of mice and voles hidden in the grasses.
Northern Harrier
It was a fitting end to a very short, but marvelously sunny, early winter day.

Visit South Mountain for the Brightest Foliage Display You’ve Ever Seen

Where should you go this weekend to see vibrantly colored foliage in our region?  Where are there eye-popping displays of reds, oranges, yellows, and greens without so much brown and gray?  The answer is Michaux State Forest on South Mountain in Adams, Cumberland, and Franklin Counties.

South Mountain is the northern extension of the Blue Ridge Section of the Ridge and Valley Province in Pennsylvania.  Michaux State Forest includes much of the wooded land on South Mountain.  Within or adjacent to its borders are located four state parks: King’s Gap Environmental Education Center, Pine Grove Furnace State Park, Caledonia State Park, and Mont Alto State Park.  The vast network of trails on these state lands includes the Appalachian Trail, which remains in the mountainous Blue Ridge Section all the way to its southern terminus in Georgia.

Pennsylvania State Parks on South Mounatin
In Pennsylvania, the forested highlands of the Blue Ridge Section of the Ridge and Valley Province are known as South Mountain.  Much of South Mountain lies within the boundaries of Michaux State Forest.  Stars indicate the locations of 1) King’s Gap Environmental Education Center, 2) Pine Grove Furnace State Park, 3) Caledonia State Park, and 4) Mont Alto State Park.  A drive on US 30 between Gettysburg and Chambersburg will take you right through Michaux State Forest along an east to west axis while a scenic northbound or southbound trip along PA 233 will bring you in proximity to each of the state parks located therein.  (Base image from NASA Earth Observatory Collection)

If you want a closeup look at the many species of trees found in Michaux State Forest, and you want them to be labeled so you know what they are, a stop at the Pennsylvania State University’s Mont Alto arboretum is a must.  Located next door to Mont Alto State Park along PA 233, the Arboretum at Penn State Mont Alto covers the entire campus.  Planting began on Arbor Day in 1905 shortly after establishment of the Pennsylvania State Forest Academy at the site in 1903.  Back then, the state’s “forests” were in the process of regeneration after nineteenth-century clear cutting.  These harvests balded the landscape and left behind the combustible waste which fueled the frequent wildfires that plagued reforestation efforts for more than half a century.  The academy educated future foresters on the skills needed to regrow and manage the state’s woodlands.

Online resources can help you plan your visit to the Arboretum at Penn State Mont Alto.  More than 800 trees on the campus are numbered with small blue tags.  The “List of arboretum trees by Tag Number” can be downloaded to tell you the species or variety of each.  The interactive map provides the locations of individual trees plotted by tag number while the Grove Map displays the locations of groups of trees on the campus categorized by region of origin.  A Founder’s Tree Map will help you find some of the oldest specimens in the collection and a Commemorative Tree Map will help you find dedicated trees.  There is also a species list of the common and scientific tree names.

Yellow Buckeye
The Yellow Buckeye (Aesculus flava) is a tree found in the forests of the Blue Ridge Section of the Ridge and Valley Province in West Virginia, Virginia, North Carolina and Georgia.  You can see it in Pennsylvania by visiting the collection of trees in the Arboretum at Penn State Mont Alto.
American Chestnut
The American Chestnut can be difficult to find due to the impact of chestnut blight, but you can see it in the Arboretum at Penn State Mont Alto.
Shagbark Hickory
Shagbark Hickory is a common tree in the forests of South Mountain.
Sweet Cherry
The Sweet Cherry (Prunus avium), a native of Europe, is naturalized throughout eastern and south-central Pennsylvania and is one of the more than 150 species of trees in the arboretum’s collection.
Sweet Birch
Sweet Birch (Betula lenta) foliage is particularly bright yellow on South Mountain this autumn.  It really “pops” against the backdrop of the evergreen Eastern White Pines and Eastern Hemlocks.  During less-than-ideal years, Sweet Birch leaves can subtly transition from green to drab brown without much fanfare before falling.
Common Persimmon
You might have a difficult time finding a Common Persimmon (Diospyros virginiana) growing wild in Pennsylvania, but you can find it in the Arboretum at Penn State Mont Alto.

The autumn leaves will be falling fast, so make it a point this weekend to check out the show on South Mountain.

A Few Plants with Wildlife Impact in June

Here’s a look at some native plants you can grow in your garden to really help wildlife in late spring and early summer.

The Larger Blue Flag (Iris versicolor) and Soft Rush (Juncus effusus) in flower in mid-June.
The showy bloom of a Larger Blue Flag (Iris versicolor) and the drooping inflorescence of Soft Rush (Juncus effusus).  These plants favor moist soils in wetlands and damp meadows where they form essential cover and feeding areas for insects, amphibians, and marsh birds.  Each is an excellent choice for helping to absorb nutrients in a rain garden or stream-side planting.  They do well in wet soil or shallow water along the edges of garden ponds too.
Smooth Shadbush
The fruits of Smooth Shadbush (Amelanchier laevis), also known as Allegheny Serviceberry, Smooth Serviceberry, or Smooth Juneberry, ripen in mid-June and are an irresistible treat for catbirds, robins, bluebirds, mockingbirds, and roving flocks of Cedar Waxwings.
Common Milkweed and Eastern Carpenter Bee
Also in mid-June, the fragrant blooms of Common Milkweed attract pollinators like Eastern Carpenter Bees,…
Common Milkweed and Honey Bee
…Honey Bees,…
Common Milkweed and Banded Hairstreak
…and butterflies including the Banded Hairstreak (Satyrium calanus).  In coming weeks, Monarch butterflies will find these Common Milkweed plants and begin laying their eggs on the leaves.  You can lend them a hand by planting milkweed species (Asclepias) in your garden.  Then watch the show as the eggs hatch and the caterpillars begin devouring the foliage.  Soon, they’ll pupate and, if you’re lucky, you’ll be able to watch an adult Monarch emerge from a chrysalis!

Mother’s Day Flowers

Let’s have a look at some of the magnificent native wildflowers blooming on this Mother’s Day in forests and thickets throughout the Lower Susquehanna River Watershed.

Rue Anemone
Rue Anemone (Thalictrum thalictroides) is a fragile little wildflower of open woods.
Blackhaw
The Blackhaw (Viburnum prunifolium) is a shrub of thickets and forest borders. The flower clusters mature into an abundance of berries relished by birds and other wildlife.
Black Cherry
A large Black Cherry tree adorned in white blossoms can be pleasing to the eye and very beneficial for pollinating insects.
Common Pawpaw
The Common Pawpaw is a small tree of damp well-drained soils.  Where conditions are ideal, it may form clonal colonies in the forest understory.  The deep maroon blooms mature into banana-like fruits, hence its alternate common name “Custard Apple”.
Mayapple
The Mayapple or Mandrake (Podophyllum peltatum) commonly blankets the forest floor.  It, like other ephemeral wildflowers, is vulnerable to invasions by non-native shrubs that leaf out earlier in spring than native species and rob them of sunlight during their already abbreviated growing season.

Aren’t they spectacular?

Why not take a stroll to have a look at these and other plants you can find growing along a nearby woodland trail?  You could check out some place new and get a little exercise too!

If you go, please tread lightly, take your camera, mind your manners, and…

Photo of the Day

Northern Walkingstick
The harmless, herbivorous Northern Walkingstick (Diapheromera femorata), also known as the Common Walkingstick, is well camouflaged when among the twigs and stems of deciduous trees.  As foliage drops in autumn, these wingless insects often descend to ground level and sometimes venture into view.  This individual was found in the vicinity of ideal habitat: a portion of forest including Black Cherry and Black Oak (Quercus velutina) trees.  Juvenile Northern Walkingsticks feed on the leaves of the former, adults on those of the latter.

Photo of the Day

Hermit Thrushes
Earlier today, these migrants were found feeding on berries along the edge of a forest clearing in northern Lebanon County, Pennsylvania.  Can you find the three Hermit Thrushes among the early successional growth seen here?   For extra credit, identify the three species of berry-producing pioneer plants that are shown.  For additional credit, which one of these plants is a non-native invasive species?   Click the image to see how you did.

Photo of the Day

Gray Catbird and Black Chokeberry
The fruits of a Black Chokeberry (Aronia melanocarpa) prove irresistible to this Gray Catbird.  Chokeberry is a native clump-forming shrub that reaches a height of less than ten feet.  It is tolerant of wet soils and makes a good choice for inclusion in plantings alongside streams and ponds, as well as in rain gardens.  Springtime clusters of white flowers yield berries by this time each summer.  By turning red as the fruits ripen, the foliage helps attract not only catbirds, but robins, waxwings, and other species that, in exchange for a meal, will assure dispersal of the plant’s seeds in their droppings.  With considerable sweetening, tart chokeberries can be used for juicing and the creation of jams, jellies, and preserves.

Photo of the Day

Invasive Trees and Plants of the Lower Susquehanna River Watershed: Callery Pear including Bradford Pear
Presently in the valleys of the Lower Susquehanna River Watershed, you’re sure to see a gorgeous nightmare, showy stands of flowering Callery Pear (Pyrus calleryana).  Invasive groves like this one quickly dominate successional habitat and often create monocultures, often excluding native pioneer trees like Eastern Red Cedar and several species of deciduous hardwood.  The void beneath the pear trees in this photograph shows how deer browsing can intensify the damage, preventing other plant species from becoming established in the understory.  In autumn, crimson foliage again makes these non-native trees a standout in the landscape.  The red leaves attract birds including American Robins and Cedar Waxwings to the abundant berries, but European Starlings usually get to them first.  Planted specimens of ornamental Callery Pears began producing fertile seeds when multiple varieties became available in addition to the self-sterile “Bradford Pears” that were planted widely during the last decades of the twentieth century.  Cross-pollination between varieties produces the fertile seeds that are distributed by starlings and other birds as they digest the fruit.

Forest vs. Woodlot

Let’s take a quiet stroll through the forest to have a look around.  The spring awakening is underway and it’s a marvelous thing to behold.  You may think it a bit odd, but during this walk we’re not going to spend all of our time gazing up into the trees.  Instead, we’re going to investigate the happenings at ground level—life on the forest floor.

Rotting logs and leaf litter create the moisture retaining detritus in which mesic forest plants grow and thrive.  Note the presence of mosses and a vernal pool in this damp section of forest.
The earliest green leaves in the forest are often those of the Skunk Cabbage (Simplocarpus foetidus).  This member of the arum family gets a head start by growing in the warm waters of a spring seep or in a stream-fed wetland.  Like many native wildflowers of the forest, Skunk Cabbage takes advantage of early-springtime sun to flower and grow prior to the time in late April when deciduous trees grow foliage and cast shade beneath their canopy.
Among the bark of dead and downed trees, the Mourning Cloak butterfly (Nymphalis antiopa) hibernates for the winter.  It emerges to alight on sun-drenched surfaces in late winter and early spring.
Another hibernating forest butterfly that emerges on sunny early-spring days is the Eastern Comma (Polygonia comma), also known as the Hop Merchant.
In a small forest brook, a water strider (Gerridae) chases its shadow using the surface tension of the water to provide buoyancy.  Forests are essential for the protection of headwaters areas where our streams get their start.
Often flooded only in the springtime, fish-free pools of water known as vernal ponds are essential breeding habitat for many forest-dwelling amphibians.  Unfortunately, these ephemeral wetland sites often fall prey to collecting, dumping, filling, and vandalism by motorized and non-motorized off-roaders, sometimes resulting in the elimination of the populations of frogs, toads, and salamanders that use them.
Wood Frogs (Lithobates sylvaticus) emerge from hiding places among downed timber and leaf litter to journey to a nearby vernal pond where they begin calling still more Wood Frogs to the breeding site.
Wood Frog eggs must hatch and tadpoles must transform into terrestrial frogs before the pond dries up in the summertime.  It’s a risky means of reproduction, but it effectively evades the enormous appetites of fish.
When the egg laying is complete, adult Wood Frogs return to the forest and are seldom seen during the rest of the year.
In early spring, Painted Turtles emerge from hideouts in larger forest pools, particularly those in wooded swamps, to bask in sunny locations.
Dead standing trees, often called snags, are essential habitats for many species of forest wildlife.  There is an entire biological process, a micro-ecosystem, involved in the decay of a dead tree.  It includes fungi, bacteria, and various invertebrate animals that reduce wood into the detritus that nourishes and hydrates new forest growth.
Birds like this Red-headed Woodpecker feed on insects found in large snags and nest almost exclusively in them.  Many species of wildlife rely on dead trees, both standing and fallen, during all or part of their lives.

There certainly is more to a forest than the living trees.  If you’re hiking through a grove of timber getting snared in a maze of prickly Multiflora Rose (Rosa multiflora) and seeing little else but maybe a wild ungulate or two, then you’re in a has-been forest.  Logging, firewood collection, fragmentation, and other man-made disturbances inside and near forests take a collective toll on their composition, eventually turning them to mere woodlots.  Go enjoy the forests of the lower Susquehanna valley while you still can.  And remember to do it gently; we’re losing quality as well as quantity right now—so tread softly.

The White-tailed Deity in a woodlot infested by invasive tangles of Multiflora Rose.

Fussy Eaters

She ate only toaster pastries…that’s it…nothing else.  Every now and then, on special occasions, when a big dinner was served, she’d have a small helping of mashed potatoes, no gravy, just plain, thank you.  She received all her nutrition from several meals a week of macaroni and cheese assembled from processed ingredients found in a cardboard box.  It contains eight essential vitamins and minerals, don’t you know?  You remember her, don’t you?

Adult female butterflies must lay their eggs where the hatched larvae will promptly find the precise food needed to fuel their growth.  These caterpillars are fussy eaters, with some able to feed upon only one particular species or genus of plant to grow through the five stages, the instars, of larval life.  The energy for their fifth molt into a pupa, known as a chrysalis, and metamorphosis into an adult butterfly requires mass consumption of the required plant matter.  Their life cycle causes most butterflies to be very habitat specific.  These splendid insects may visit the urban or suburban garden as adults to feed on nectar plants, however, successful reproduction relies upon environs which include suitable, thriving, pesticide-free host plants for the caterpillars.  Their survival depends upon more than the vegetation surrounding the typical lawn will provide.

The Monarch (Danaus plexippus), a butterfly familiar in North America for its conspicuous autumn migrations to forests in Mexico, uses the milkweeds (Asclepias) almost exclusively as a host plant.  Here at  Conewago Falls, wetlands with Swamp Milkweed (Asclepias incarnata) and unsprayed clearings with Common Milkweed (A. syriaca) are essential to the successful reproduction of the species.  Human disturbance, including liberal use of herbicides, and invasive plant species can diminish the biomass of the Monarch’s favored nourishment, thus reducing significantly the abundance of the migratory late-season generation.

Monarch caterpillar after a fourth molt.  The fifth instar feeding on Swamp Milkweed.
A fifth molt begets the Monarch pupa, the chrysalis, from which the showy adult butterfly will emerge.
Adult Monarch feeding on Goldenrod (Solidago) nectar.

Butterflies are good indicators of the ecological health of a given environment.  A diversity of butterfly species in a given area requires a wide array of mostly indigenous plants to provide food for reproduction.  Let’s have a look at some of the species seen around Conewago Falls this week…

An adult Silvery Checkerspot (Chlosyne nycteis) visiting a nectar plant, Partridge Pea (Chamaecrista fasciculata).  Wingstem (Verbesina alternifolia), a plant of the Riparian Woodlands, is among the probable hosts for the caterpillars.
A Gray Hairstreak (Strymon melinus) visits Crown Vetch, a possible host plant.  Other potential larval food in the area includes Partridge Pea, Halberd-leaved Rose Mallow (Hibiscus laevis) of the river shoreline, and Swamp Rose Mallow (Hibiscus moscheutos), a plant of wetlands.
The Eastern Tailed Blue (Cupido comyntas) may use Partridge Pea , a native wildflower species, and the introduced Crown Vetch (Securigera/Coronilla varia) as host and nectar plants at Conewago Falls.
The Least Skipper (Ancyloxypha numitor) is at home among tall grasses in woodland openings, at riverside, and in the scoured grassland habitat of the Pothole Rocks in the falls.  Host plants available include Switchgrass (Panicum vigatum), Freshwater Cordgrass (Spartina pectinata), and Foxtails (Setaria).
The Zabulon Skipper (Poanes zabulon) is an inhabitant of moist clearings where the caterpillars may feed upon Lovegrasses (Eragrostis) and Purpletop (Tridens flavus).
The Eastern Tiger Swallowtail (Papilio glaucus), a female seen here gathering nectar from Joe-Pye Weed (Eutrochium), relies upon several forest trees as hosts. Black Cherry (Prunus serotina), Willow (Salix), Yellow Poplar (Liriodendron tulipifera), also known as Tuliptree, and Green Ash (Fraxinus pennsylvanica) are among the local species known to be used.  The future of the latter food species at Conewago Falls is doubtful.  Fortunately for the Eastern Tiger Swallowtail, the “generalist” feeding requirements of this butterfly’s larvae enable the species to survive the loss of a host plant.
A female Eastern Tiger Swallowtail, black morph, gathering nectar from Joe-Pye Weed.
The Zebra Swallowtail (Protographium marcellus), an adult seen here on Joe-Pye Weed, feeds exclusively upon Pawpaw (Asimina) trees as a caterpillar.  This butterfly species may wander, but its breeding range is limited to the moist Riparian Woodlands where colonial groves of Pawpaw may be found.  The Common Pawpaw (Asimina triloba), our native species in Pennsylvania, and the Zebra Swallowtail occur at the northern edge of their geographic ranges in the Lower Susquehanna River Watershed.  Planting Pawpaw trees as an element of streamside reforestation projects certainly benefits this marvelous butterfly.

The spectacularly colorful butterflies are a real treat on a hot summer day.  Their affinity for showy plants doubles the pleasure.

By the way, I’m certain by now you’ve recalled that fussy eater…and how beautiful she grew up to be.

SOURCES

Brock, Jim P., and Kaufman, Kenn.  2003.  Butterflies of North America.  Houghton Mifflin Company.  New York, NY.