Pipevine swallowtail eggs on snake apple
June 27, 2026
Along the rocky slopes and cedar edges near Austin, snake apple vines are climbing whatever they can find right now. The stems are thin and wiry, the leaves deeply lobed, and the small yellow-green fruits hang where flowers were a few weeks ago. It is easy to walk past this plant without stopping. But look closely at the undersides of the leaves, and in early summer you may find what you are looking for: small clusters of rust-orange eggs, each one the size of a pinhead, laid in tight groups by the pipevine swallowtail.The pipevine swallowtail is a large butterfly, dark-winged with an iridescent blue-green sheen on the hindwings that catches the light when it moves through dappled shade. The adults nectar widely, visiting wax mallow and other open flowers in the heat of the day. But for laying eggs, the female is specific. She seeks out snake apple, and a handful of other native pipevines in the region, because the plant contains aristolochic acids, a group of compounds that are toxic to most insects and to vertebrates. The caterpillars that hatch from those orange eggs are not harmed by these compounds. Instead, they eat the leaves and incorporate the acids into their own tissues.The caterpillars start small and dark, almost black, with rows of fleshy orange tubercles along their backs. As they grow through their instars, the color intensifies. By the time they are fully grown, they are conspicuous: dark brown to reddish-black, those orange knobs prominent, the body thick and slow-moving on the vine. This is not camouflage. The coloration is a signal. Birds that have tried eating one of these caterpillars, or the adult butterflies that emerge from them, learn the association. The bright colors and the bad taste reinforce each other. A blue jay that samples a pipevine swallowtail larva once tends not to try again.What makes this relationship ecologically interesting is how it extends beyond the two species directly involved. Several other butterfly species in this region, including the red-spotted purple and certain female tiger swallowtails, have wing patterns that closely resemble the adult pipevine swallowtail. They do not carry the aristolochic acids themselves, but they benefit from the learned aversion that predators have developed toward the pipevine's coloration. The pipevine swallowtail is the anchor of that mimicry system, and the anchor depends entirely on snake apple being present in the landscape.Snake apple is a native vine of the Texas Hill Country and the Edwards Plateau, well adapted to thin limestone soils and summer drought. It dies back to a tuberous root in winter and leafs out again in spring, which is why the pipevine swallowtail's egg-laying tracks the vine's growing season so closely. The female butterfly is not simply finding a food source; she is finding the one plant whose chemistry her offspring can use. How she locates individual vines, which can be sparse and scattered across a landscape, is not fully resolved, but contact with the leaf surface appears to trigger the decision to lay. She lands, drums with her forelegs, and within seconds either moves on or begins depositing eggs.Right now, in the long days of early summer, the vines are in full leaf and the first egg clusters are appearing. If you find a snake apple vine and check the undersides of several leaves, you may find eggs, young larvae, or the characteristic feeding damage where a caterpillar has taken irregular bites from the blade. The caterpillars do not strip a plant bare; they move between leaves, and a healthy vine can support a small cohort without losing too much tissue. The relationship is close but not destructive, calibrated over a long association between this butterfly and the plants in this genus.The air near Austin is thick and warm by mid-morning now, and the light comes down hard through the cedar and oak. Somewhere in the scrubby edges, a pipevine swallowtail is working the understory, wings tilting as it moves from shade to sun and back again.
Waller Creek flow drops to zero in July drought
July 14, 2026
The creek ran dry this week. A month ago, flow measured 165 cubic feet per second — a modest but steady pulse through the summer channel. Now the gauge reads zero, and the aquifer springs that feed these karst streams have stopped flowing.When flow ceases, aquatic life has nowhere to go but the remaining pools. Fish, invertebrates, and plants compress into shrinking refuge pools where July heat climbs toward 100°F and oxygen crashes. These congested refuges become ecological traps — temporary, stressed, unsustainable. The creek's impaired waters listing exists precisely for moments like this, when the system can no longer support the life it normally carries.Karst streams in summer depend entirely on springs. Once the aquifer stops delivering water, collapse comes fast.
Sharp-shinned hawk hunts through summer neighborhoods
June 12, 2026
The morning air carries the soft chip notes of kinglets through the residential canopy near Austin, where live oaks spread their broad crowns over sidewalks and driveways. Ruby-crowned kinglets move through the upper branches in quick, nervous hops, their olive backs catching the early light as they glean insects from the undersides of leaves. These small birds are uncommon here in summer, lingering briefly as they follow migration routes that carry them far beyond Texas heat.A sharp-shinned hawk materializes between the houses, its short wings beating in rapid bursts before it glides low through the yard spaces. This small raptor moves like water through obstacles, threading between fence posts and porch railings with a precision that transforms suburban geometry into hunting ground. Sharp-shinned hawks are built for pursuit in tight spaces. Their long tails act as rudders, their compact bodies slip through gaps that would stop larger raptors. In summer, when most of their kind have moved north to breed, this individual has stayed to exploit the brief abundance of migrating songbirds that pause in Austin neighborhoods.The hawk's presence changes everything. Kinglets that were feeding openly moments before now freeze against bark, their movements reduced to the smallest necessary adjustments. A least flycatcher, another uncommon summer visitor, abandons its perch on a redbud branch where the tree's heart-shaped leaves provide little cover. These small flycatchers normally dart out to catch insects in midair before returning to the same perch, but the hawk's arrival breaks this rhythm. The flycatcher drops into the dense growth of American beautyberry, where purple flower clusters are just beginning to form and the layered branches offer better protection.The relationship between this hawk and its prey operates on split-second timing. Sharp-shinned hawks hunt by surprise, using cover to approach within striking distance before launching into open pursuit. Their short, rounded wings generate quick acceleration but sacrifice the sustained speed of larger raptors. This means the chase must be decisive. Either the hawk catches its target in the first rush, or the songbird reaches cover and escapes. Kinglets and flycatchers have evolved responses to this pressure. They feed with constant awareness, heads turning frequently to scan for movement. When threatened, they drop into dense vegetation where the hawk's advantage disappears.The summer neighborhoods provide an unusual hunting ground for this hawk. Residential plantings create a patchwork of open areas and thick cover, with bird feeders and flowering shrubs concentrating small birds in predictable locations. The wax mallow blooms are drawing insects, which in turn attract the flycatchers and kinglets. These temporary abundances give the sharp-shinned hawk opportunities that would not exist in more uniform habitat. The bird moves between yards like it knows the territory, appearing suddenly at the edge of one property before vanishing behind a garage and emerging in the next block.
