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.
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.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.
The Yellow-throated Vireo nests, feeds, and spends the majority of its time feeding among canopy foliage.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.The Northern Parula nests in mature forests along rivers and on mountainsides, particularly where mature trees are draped with thick vines.The Hooded Warbler (Setophaga citrina) is found among thick understory growth on forested slopes.The Ovenbird builds a domed, oven-like nest on the ground and forages in the canopy.The Kentucky Warbler (Geothlypis formosa) nests in woodland undergrowth, often near steep, forested slopes.The Worm-eating Warbler (Helmitheros vermivorum) nests among woody understory growth on forested hillsides.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 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.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.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.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.
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.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.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.Adapt and Reuse- A Red-eyed Vireo visits an Eastern Tent Caterpillar nest……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.
Our Lucky Break- This Scarlet Tanager descended from the treetops to feed on spiders in a small forest clearing.
Back in late May of 1983, four members of the Lancaster County Bird Club—Russ Markert, Harold Morrrin, Steve Santner, and your editor—embarked on an energetic trip to find, observe, and photograph birds in the Lower Rio Grande Valley of Texas. What follows is a daily account of that two-week-long expedition. Notes logged by Markert some four decades ago are quoted in italics. The images are scans of 35 mm color slide photographs taken along the way by your editor.
DAY EIGHT—May 28, 1983
“Bentsen State Park, Texas”
“Alarm at 6:00 A.M. After breakfast we traveled to Falcon State Park and toured the whole camp area, stopping many places to observe birds. We ran up a good list.”
And so we left what had been our home for the last several days and headed west. In the forty years since our departure that morning, Bentsen-Rio Grande State Park has experienced a number of operational changes. Today, it is a World Birding Center site. For conducting the seasonal hawk census, a tower has been erected to provide counters and observes with an unrestricted view above the treetops. If you wanted to camp in the park now, you would need reservations and would have to hike your gear in to one of only a few primitive campsites. Trailer and motor home accommodations no longer exist. A tram service is now available for touring the park by motor vehicle.
West of Rio Grande City, we exited the river’s outflow delta and entered the Texas scrubland, an area mostly devoid of large trees except in moist soils immediately adjacent to the Rio Grande where the lush vegetation creates a dense subtropical riparian forest in many places. The reservoir itself is known to attract migrating and vagrant waterfowl, waders, shorebirds, gulls, terns, and seabirds. (United States Fish and Wildlife Service base image)
Falcon State Park is located along the east shore of Falcon Reservoir. There are no shade trees beneath which one can escape the scorching rays of the sun on a hot day. This is the easternmost section of the scrubland’s Tamaulipan Saline Thornscrub, a xeric plant community of head-high brush found only on clay soils with a particularly high salinity. Many of the plants look similar to other varieties of shrubs and small trees with which one may be familiar, except nearly all of them are covered with nasty thorns and prickles. And yes, there are cactus. You can’t make your way bushwhacking cross country without obtaining cuts, gashes, and scars to show for it. The Falcon State Recreation Area bird checklist published in 1977 has a nice description of the plants found there—mesquite, ebano, guaycan, blackbrush and catclaw acacia, granjeno, coyotillo, huisache, tasajillo, prickly pear, allthorn, cenizo, colima, and yucca. In the margins between the thornscrub growth, there is an abundance of grasses and wildflowers. On nearby ridges, Tamaulipan Calcareous Thornscrub, a similar xeric plant community, occupies soils with a higher content of calcium carbonate. Together, these communities comprise much of the Tamaulipan Mezquital ecoregion of scrublands in Starr County and western Hidalgo County in the Rio Grande valley of Texas.
After being greeted by a Greater Roadrunner at the campsite, we took a walk to the nearby shoreline of the reservoir. We spotted Olivaceous Cormorants perched on some dead limbs in the water nearby. Known today as Neotropic Cormorant (Phalacrocorax brasilianus), it is yet another specialty of the Rio Grande Valley. Elsewhere on or near the water—Cattle Egret, Great Egret, Black-bellied Whistling Duck, Osprey, Common Gallinule, Killdeer, Laughing Gull, Forster’s Tern (Sterna forsteri), Least Tern, and Caspian Tern were seen.
The Greater Roadrunner is right at home in the Tamaulipan Saline Thornscrub habitat in and around Falcon State Park. This one came to check us out soon after our arrival at our campsite. Roadrunners prey on insects, rodents, and lizards including the Texas Spotted Whiptail (Aspidoscelis gularis), a species which we found nearby.
In the thornscrub around the campground, which, like Bentsen-Rio Grande State Park, we had pretty much to ourselves, we saw Scissor-tailed Flycatcher, Curve-billed Thrasher, White-winged Dove, Mourning Dove, Ground Dove, Inca Dove, and White-tipped Dove. A single Chihuahuan Raven was a fly by. We saw and smelled several road-killed Nine-banded Armadillos (Dasypus novemcinctus), but never found one alive.
Then, it started to rain. Not just a shower, but a soaker that persisted through much of the day. Rainy days can make for great birding, so we kept at it. Unfortunately, such days aren’t too ideal for photography, so we did only what we could without ruining our equipment.
In the campground at Falcon State Park, a Cactus Wren (Campylorhynchus brunneicapillus) takes shelter from the rain beneath a canopy protecting a picnic table.Looks like a good idea, others soon sought shelter there as well.
“Finally we drove to the spillway of the dam and parked.”
Falcon Dam was another of the numerous flood-control projects built on the Rio Grande during the middle of the twentieth century. Behind it, Falcon Reservoir stores water for irrigation and operation of a hydroelectric generating station located within the dam complex. Construction of the dam and power plant was a joint venture shared by Mexico and the United States. The project was dedicated by Presidents Adolfo Ruiz Cortines and Dwight D. Eisenhower in 1953.
Rainy days aside, the route precipitation takes to reach the Falcon Reservoir and the Lower Rio Grande Valley includes hundreds of miles through arid grasslands and scrublands. Along the way, much of that water is lost to natural processes including evaporation and aquifer recharge, but an increasing percentage of the volume is being removed by man for civil, industrial, and agricultural uses. Can the Rio Grande and its tributaries continue to meet demand?
The Rio Grande’s headwaters can be found in south-central Colorado where spring snow melt is vital to establishing adequate flow to allow the river to recharge aquifers in the hundreds of miles of arid lands through which it flows. Presently, dams in the upper reaches of the river are operated to hold water during the spring thaw, then release it slowly to compensate for base flow lost to withdrawals for irrigation in extensive areas of the middle reaches of the watershed. With everyone wanting their take, is there enough water to go around? Diminishing ground water levels suggest the answer is no. (National Oceanic and Atmospheric Administration base image)Using the streamflow recharge process, the flowing Rio Grande provides water to the aquifers in the arid regions through which it passes. Click the image for a slightly larger version. (United States Geological Survey image)
“On the way in we saw and photographed an apparent sick or injured Swainson’s Hawk. We approached it very close.”
The Swainson’s Hawk (Buteo swainsoni), a bird of prairies and other grasslands, is an abundant migrant through the Lower Rio Grande Valley in both spring and fall. This one was grounded, rain-soaked, and obviously running late. Others of its kind were by now on their breeding grounds in the Great Plains and Rocky Mountains.The bird allowed us to approach without attempting to flee, which isn’t a good sign. We looked for any obvious physical injuries and found none.The continuous rain had the hawk’s feathers matted down and soaked.Was its water-logged plumage the problem, or was it the result of its inability to thrive due to an illness? We had no way of telling, so we let it be and vowed to stop back later to check on it.Steve the hawk whisperer?
“At the spillway we sat in the camper, except when the rain slackened, then we stood out and watched in vain for the Green or Ringed Kingfisher, which we never did see.”
At the spillway House Sparrows, Rough-winged Swallows, and Cliff Swallows were nesting on the dam, the latter two species grabbing flying insects above the waters of the Rio Grande.
Despite the rain, anglers were fishing along the spillway walls where this young man caught a Longnose Gar (Lepisosteus osseus). The reservoir has been stocked with Alligator Gar (Atractosteus spatula), Spotted Gar (Lepisosteus oculatus), and a variety of bass, catfish, and other species to establish a trophy sport fishery. Many specimens grow to become trophy-size there due to the warm water temperatures. These guys though were fishing for food, not trophies.
“I made dinner here at this spillway and we continued to watch. The rain almost stopped, so we walked down the road about 1 1/2 miles, during which time we saw a lifer for Harold — Hook-billed Kite. We followed Father Tom’s directions to a spot for the Ferruginous Owl — no luck.”
A Red-billed Pigeon in a willow tree in the subtropical riparian forest along the banks of the Rio Grande below Falcon Dam. Prior to this trip, neither Steve nor I had ever seen this tropical species before.
“Back at the spillway we had supper and then repeated the hike — no Ferruginous Owl, but a Barn Owl and Great Horned Owl. Back to our #201 campsite and wrote up the day’s log.”
Trees along the river provided habitat for orioles and other species. Since the rain had subsided, we decided to see what might come out and begin feeding. Soon, we not only saw an Altamira Oriole, but found Hooded Oriole (Icterus cucullatus) and the yellow and black tropical species, Audubon’s Oriole (Icterus graduacauda), formerly known as Black-headed Oriole. Three species of orioles on a backdrop of lush green subtropical foliage, it was magnificent.
Along the dirt road below the dam, the mix of scrubland and subtropical riparian forest made for excellent birding. We not only found a soaring Hook-billed Kite, one of the target birds for the trip, but we had good looks at both a Great Horned Owl, then a Barn Owl (Tyto alba) that we flushed from the bare ground in openings among the vegetation as we walked the through. Both had probably pounced on some sort of small prey species prior to our arrival. Because there are seldom crows or ravens to bother them, owls here are more active during than day than they are elsewhere. The subject of this afternoon’s intensive search, the elusive and diminutive Ferruginous Pygmy Owl (Glaucidium brasilianum), is routinely diurnal. Other sightings on our two walks included Turkey Vulture, Black Vulture, White-tailed Kite, Northern Bobwhite, Yellow-billed Cuckoo, Golden-fronted Woodpecker, Ladder-backed Woodpecker, Couch’s Kingbird, Brown-crested Flycatcher, Green Jay, Black-crested Titmouse, Mockingbird, Long-billed Thrasher, Great-tailed Grackle, Bronzed Cowbird, Northern Cardinal, and Painted Bunting.
The day finished as so many others had earlier during the trip—with insect-hunting Common Nighthawks calling from the skies around our campsite.
Back in late May of 1983, four members of the Lancaster County Bird Club—Russ Markert, Harold Morrrin, Steve Santner, and your editor—embarked on an energetic trip to find, observe, and photograph birds in the Lower Rio Grande Valley of Texas. What follows is a daily account of that two-week-long expedition. Notes logged by Markert some four decades ago are quoted in italics. The images are scans of 35 mm color slide photographs taken along the way by your editor.
DAY FIVE—May 25, 1983
Bentsen State Park, Texas
Went to bed last nite about 11:30. Did not set the alarm. Very hot — Awoke at 7:30 A.M. We circled the campground and then drove to the river trail. We walked to the river, getting more lifers for Larry — Couch’s Kingbird, Olive Sparrow, and Groove-billed Ani. The Couch’s Kingbird is my first lifer of the trip. The Olive Sparrow has the same cadence as the Tennessee Warbler. We then checked the resaca and found a Least Bittern.
While checking out the cattails at the resaca, we failed to catch a glimpse of a Coues’ Rice Rat (Oryzomys couesi), a semi-aquatic mammal that lives only in the Rio Grande Valley and areas south into Central America. Instead we found an Eastern Fox Squirrel (Sciurus niger), a giant compared to the gray squirrels in Pennsylvania. Things really are bigger in Texas.
This Couch’s Kingbird (Tyrannus couchii) was a “lifer” for both Russ and your editor; neither of us had ever seen one before. (Vintage 35 mm image)
Back to our camp site for lunch, after paying for our stay at the office. P.M. — Put out corn and sunflower seeds and loafed all P.M. trying to get pictures. Larry had a lot of luck. I did not do so good.
Plain Chachalacas, White-winged Doves, White-tipped Doves, Great-tailed Grackles, and a Bronzed Cowbird stopped by to sample the seed offerings. The chachalacas and grackles created quite a racket. It’s a good thing we didn’t have any neighbors close by!
Great-tailed Grackles visit Russ’ makeshift feeding station. These giants are 50% larger than the Common Grackles with which I was familiar. Yes, even the blackbirds are bigger in Texas. (Vintage 35 mm image)A Bronzed Cowbird picks up some seed morsels. (Vintage 35 mm image)
In nearby areas of the campground there were many species—Black-bellied Whistling Duck, Anhinga, Great Egret, Common Gallinule, Turkey Vulture, Yellow-billed Cuckoo, Golden-fronted Woodpecker, Ladder-backed Woodpecker, Eastern Kingbird, Brown-crested Flycatcher, Curve-billed Thrasher, Long-billed Thrasher (Toxostoma longirostre), Altamira Oriole, and Northern Cardinal.
A Golden-fronted Woodpecker peers from its nest cavity. (Vintage 35 mm image)The two thrasher species found in the campground highlighted the mix of two unique habitats. The Curve-billed Thrasher is a species of scrubland while this Long-billed Thrasher is more typically an inhabitant of bottomlands. (Vintage 35 mm image)
Rain is rare here — The rainy season produced no rain. Now a light rain is falling. The temperature dropped to 90° in the camper. One couple wanted to see anis. Larry picked one out 50 ft. from their campsite.
The Groove-billed Ani (Crotophaga sulcirostris) is a large-billed relative of the cuckoos. Because it is totally black in color, it can be very difficult to spot among the dense foliage where it typically feeds. It ranges north from Mexico only into south Texas. (Vintage 35 mm image)
The rain cooled the air to make the evening tolerable, but we would pay for it tomorrow with an increase in the humidity.
A Green Jay during the evening rain. (Vintage 35 mm image)
We paid for another nite and at dusk went to the Elf Owl tree where eventually 4 young came out and tried their wings and crawled around. The two adults flew in and Larry was ecstatic taking pictures with his strobe light. We met some people. One couple never saw Eastern Bluebirds. I gave him my card. Another couple pinpointed the owl tree.
This evening was certainly highlighted by the emergence of the young Elf Owls (Micrathene whitneyi) from their nest cavity. But in addition, we again heard the sounds of some of the other nocturnal birds found in the park—Common Nighthawk, Common Pauraque, and Eastern Screech Owl.
The Elf Owl is a species of desert bottomlands and canyons throughout southwestern portions of the United States and northwestern Mexico. Bentsen-Rio Grande State Park and the adjacent areas of Hidalgo County, Texas, are about as far east as they get. Look closely and you may discern two juveniles emerging from their nest cavity in a large tree. (Vintage 35 mm image)Juvenile Elf Owls checking out the visitors. (Vintage 35 mm image)Juvenile Elf Owls having a look around. (Vintage 35 mm image)One of the adult Elf Owls arrives. In the desert, these tiny owls often nest and roost in a hollow portion of a standing cactus. (Vintage 35 mm image)One of four juvenile Elf Owls seen at the Bentsen-Rio Grande Valley State Park nest site. (Vintage 35 mm image)
The southbound bird migration of 2020 is well underway. With passage of a cold front coming within the next 48 hours, the days ahead should provide an abundance of viewing opportunities.
Here are some of the species moving through the lower Susquehanna valley right now.
Blue-winged Teal are among the earliest of the waterfowl to begin southward migration.Sandpipers and plovers have been on the move since July. The bird in the foreground with these Killdeer is not one of their offspring, but rather a Semipalmated Plover (Charadrius semipalmatus), a regular late-summer migrant in the Lower Susquehanna River Watershed.Hawk watch sites all over North America are counting birds right now. The Osprey is an early-season delight as it glides past the lookouts. Look for them moving down the Susquehanna as well.Bald Eagles will be on the move through December. To see these huge raptors in numbers, visit a hawk watch on a day following passage of a cold front when northwest winds are gusting.Merlins were seen during this past week in areas with good concentrations of dragonflies. This particular one at Middle Creek Wildlife Management Area in Lancaster and Lebanon Counties……was soon visited by another.Check the forest canopy for Yellow-billed Cuckoos. Some local birds are still on breeding territories while others from farther north are beginning to move through.Ruby-throated Hummingbirds are darting through the lower Susquehanna valley on their way to the tropics. This one has no trouble keeping pace with a passing Tree Swallow.Nocturnal flights can bring new songbirds to good habitat each morning. It’s the best time of year to see numbers of Empidonax flycatchers. But, because they’re often silent during fall migration, it’s not the best time of year to easily identify them. This one lacking a prominent eye ring is a Willow Flycatcher (Empidonax traillii).During the past two weeks, Red-eyed Vireos have been numerous in many Susquehanna valley woodlands. Many are migrants while others are breeding pairs tending late-season broods.During mornings that follow heavy overnight flights, Blackburnian Warblers have been common among waves of feeding songbirds.Chestnut-sided Warblers are regular among flocks of nocturnal migrants seen foraging among foliage at sunrise.Scarlet Tanagers, minus the brilliant red breeding plumage of the males, are on their way back to the tropics for winter.While passing overhead on their way south, Bobolinks can be seen or heard from almost anywhere in the lower Susquehanna valley. Their movements peak in late August and early September.During recent evenings, Bobolinks have been gathering by the hundreds in fields of warm-season grasses at Middle Creek Wildlife Management Area.If you go to see the Bobolinks there, visit Stop 3 on the tour route late in the afternoon and listen for their call. You’ll soon notice their wings glistening in the light of the setting sun as they take short flights from point to point while they feed. Note the abundance of flying insects above the Big Bluestem and Indiangrass in this image. Grasslands like these are essential habitats for many of our least common resident and migratory birds.
One can get a stiff neck looking up at the flurry of bird activity in the treetops at this time of year. Many of the Neotropical migrants favor rich forests as daytime resting sites after flying through the night. For others, these forests are a destination where they will nest and raise their young.
The Veery (Catharus fuscescens) is a Neotropical thrush that breeds in extensive mature forest on the dampest slopes of the Diabase ridges in the Gettysburg Basin. Their rolling flute-like songs echo through the understory as newly arrived birds establish nesting territories.The whistled song of the Baltimore Oriole is often heard long before this colorful Neotropical is seen among the foliage of a treetop. Some dead branches allow us a glimpse of this curious beauty.The “Pee-a-wee……..Pee-urr” song of the Eastern Wood-Pewee (Contopus virens), a small flycatcher, is presently heard in the Riparian Woodlands at Conewago Falls. It breeds in forested tracts throughout the lower Susquehanna valley. The vocalizations often continue through the summer, ending only when the birds depart to return to the tropics for the winter.While constructing a nest beneath a tree canopy, an Eastern Wood-Pewee form-fits the cup where eggs will soon be laid.The Yellow-billed Cuckoo (Coccyzus americana) nests in the treetops of Riparian Woodlands along the Susquehanna and its tributaries. Most arrive during the second half of May for their summer stay. It is a renowned consumer of caterpillars.The Cedar Waxwing is a notorious wanderer. Though not a Neotropical migrant, it is a very late nester. Flocks may continue moving for another month before pairs settle on a place to raise young.Of the more than twenty species of warblers which regularly migrate through the lower Susquehanna Valley, the Common Yellowthroat (Geothlypis trichas) is among those which breeds here. It is particularly fond of streamside thickets.
For the birds that arrive earlier in spring than the Neotropical migrants, the breeding season is well underway. The wet weather may be impacting the success of the early nests.
Northern Rough-winged Swallows arrived back in April. At traditional nest sites, including the York Haven Dam and local creek bridges, small groups of adults were seen actively feeding and at times perching in dead treetops during recent days. There was an absence of visits to the actual nest cavities where they should be feeding and fledging young by now. It’s very possible that these nests failed due to the wet weather and flooding. Another nest attempt may follow if drier conditions allow stream levels to subside and there is an increase in the mass of flying insects available for the adults to feed to their young..A Carolina Chickadee, a resident species, is seen atop a hollow stump where it and a mate are constructing a new nest for a second brood. Did the first brood fail? Not sure.Common Mergansers are an uncommon but regular nesting species of waterfowl on the lower Susquehanna River. They nest in cavities, requiring very large trees to accommodate their needs. It was therefore encouraging to see this pair on a forested stream in northern Lancaster County during the weekend. However, a little while after this photograph was taken the pair flew away, indicating that they are not caring for young which by now should be out of the nest and on the move under the watchful care of the female.
So long for now, if you’ll excuse me please, I have a sore neck to tend to.
