Gray treefrogs call through the longest nights
June 5, 2026
The air holds its warmth past ten o'clock near Asheville, and from the wetlands comes a sound like distant machinery. Gray treefrogs have emerged from their daytime roosts in the bark crevices and hollow stems where their mottled skin renders them invisible. Now, as darkness settles over the ponds and slow streams, the males position themselves on low branches and begin their territorial calls.The gray treefrog spends most of its life as a solitary hunter, climbing through shrubs and low trees with the adhesive pads on its toes. Its skin shifts from gray to green to brown, matching whatever surface it rests against during the day. But early summer transforms these cryptic climbers into something else entirely. The males gather at the water's edge, their throat sacs inflating like pale balloons as they produce their prolonged trills. Each call lasts several seconds, a steady vibration that carries across the water and through the humid air.This timing connects to more than just the calendar. Aquatic insects are emerging from the ponds and streams in waves during these longest days. Midges, mayflies, and caddisflies complete their underwater larval stages and rise to the surface, where they molt into their winged adult forms. The gray treefrogs feed heavily on these emerging insects, building the energy reserves they need for breeding. More importantly, the same insect emergence will sustain their tadpoles once the eggs are laid and hatched. The female treefrogs deposit their eggs in shallow, temporary pools where the water warms quickly and algae blooms provide food for the developing larvae. These pools teem with the same aquatic invertebrates that drew the adults to breed here.Green frogs call from deeper water nearby, their single-note banjo twangs punctuating the treefrogs' sustained trills. The two species partition the acoustic space, the green frogs calling from permanent ponds while the gray treefrogs choose the shallower, more temporary waters. Each species times its breeding to match the peak availability of different food sources. The green frog tadpoles will overwinter in the deep water, feeding on detritus and algae through the cold months. The gray treefrog tadpoles must complete their entire development before their shallow pools dry up or freeze, racing through metamorphosis in a matter of weeks.The calls continue past midnight, when the air finally begins to cool and dew starts to form on the grass stems. If you step outside now, the mechanical trill of the gray treefrogs carries across the darkness, steady and insistent, marking the peak of their brief breeding window in the longest nights of the year.
Warblers and the spring leaf-out feast
May 21, 2026
The canopy at State Game Lands 267 has reached full leaf-out, and the forest hums with a different energy than it held just weeks ago. Fresh leaves unfurl in every shade of green, from the pale yellow-green of new oak to the deeper emerald of mature maple. If you're walking beneath these trees, you might notice something else: the constant movement in the branches above, quick flickers of yellow and black and white weaving through the foliage.Black-and-white Warblers spiral up the trunks like living bark, their striped patterns breaking up their outline as they probe for insects hiding in the crevices. Chestnut-sided Warblers dart between the outer branches, their bright yellow caps catching the filtered light as they snap up caterpillars from the undersides of leaves. Black-throated Blue Warblers work the middle story, the males' deep blue backs contrasting sharply with the green backdrop as they glean insects from branch to branch. Each species occupies its own layer and hunting method, but they're all here for the same reason: the explosion of insect life that follows the spring leaf-out.This timing is no accident. As the trees push out their tender new growth, caterpillars emerge to feed on these protein-rich young leaves. The Hickory Tussock Moth caterpillars, fuzzy white with black tufts, appear just as the hickory and walnut leaves reach their most nutritious stage. Other moth and butterfly larvae follow similar schedules, each species synchronized with its preferred host plants. The result is a brief but intense period when the forest canopy becomes a banquet table loaded with soft-bodied, protein-packed prey. For the warblers, this feast couldn't come at a better time. They've just completed their spring migration, burning through fat reserves to fuel thousands of miles of flight. Now they need to rebuild their energy stores and, for many species, prepare for the demands of breeding season. The abundance of caterpillars provides exactly what they need: high-quality protein in easily digestible packages. A single Black-and-white Warbler can consume hundreds of small caterpillars in a day, each one helping to restore the bird's condition after its long journey north. The Chestnut-sided Warblers, many of them establishing territories and courting mates, require this protein boost to produce eggs and feed their eventual nestlings. The relationship runs deeper than simple predation. The warblers help control insect populations that might otherwise defoliate the trees, while the insects provide the energy that allows these birds to successfully reproduce in Pennsylvania's forests. The timing window is narrow. Peak caterpillar abundance lasts only a few weeks, and the warblers have evolved to arrive precisely when this resource becomes available. Miss the window, and breeding success plummets. Arrive too early, and there's not enough food to sustain the energy demands of territory defense and courtship.
Chimney swifts over the early summer emergence
June 25, 2026
Look up. Over the open ground at SGL 198, chimney swifts are cutting arcs across the sky, chattering as they go. That high, thin chipping call is almost continuous when a group is working the air above a field or water. The birds themselves are small and dark, with a stiff, flickering wingbeat unlike any swallow — they look as though they are beating both wings alternately rather than together, though they are not. What they are doing up there, right now, is feeding. And what they are feeding on is the early summer emergence of aquatic insects.Mayflies and caddisflies spend most of their lives underwater. Mayfly nymphs live in stream gravel and leaf litter for months, sometimes more than a year, grazing on algae and organic debris. Caddisfly larvae build cases from sand grains or plant fragments and do the same. Then, in early summer, they transform and leave the water. Mayflies emerge as winged adults that cannot feed at all — their mouthparts are vestigial, their digestive systems reduced. They have hours or days to find a mate and deposit eggs before they die. Caddisflies live a little longer as adults but are similarly driven by the narrow window of their emergence. Both emerge in large numbers over short periods, which concentrates them in the air above streams and ponds at predictable times. Chimney swifts find them there.A swift forages entirely on the wing. It drinks on the wing, skimming a water surface. It collects nesting material on the wing, snapping dead twigs from treetops as it passes. During nesting season, the adults must catch enough insects not only to sustain themselves but to carry back to nestlings in whatever chimney or hollow tree they have claimed. Swifts compress multiple insects into a mass in their throat pouch before returning to the nest. A single feeding trip can deliver dozens of small insects at once. The aquatic emergence matters because it produces exactly what the birds need: large numbers of soft-bodied, protein-rich insects concentrated in open airspace over water, reliably, at the time of year when nestlings are growing fastest.The swifts at SGL 198 are working the open fields and edges near the strip mine areas, which likely drain into small streams and wet areas. Those drainages, even modest ones, produce mayflies and caddisflies. The birds range widely from their nest sites — several kilometers is unremarkable — so a swift nesting in a chimney in Ashville may be foraging over water a mile or more away. Other aerial insectivores are doing the same thing. Eastern phoebes and eastern wood-pewees are both present here, taking insects in sallying flights from exposed perches at the forest edge. They are working a different layer of the same emergence, catching insects closer to vegetation rather than high in open air. The resource is large enough that the birds partition it by flight style and hunting height without much direct competition.
