Flat to Rolling Plains

Pale Snaketail dragonflies emerged this month along the South Platte River — a finding that carries weight in an urban waterway. These elegant damselflies (Gomphus pallida) require clean, well-oxygenated streams with gravelly bottoms to complete their aquatic nymph stage, which typically spans two to four years buried in sediment. A single adult snaketail is therefore a window not into this season's conditions, but into water quality that held steady years in the past, when that nymph was developing.That context makes the current crisis harder to reconcile. Dissolved oxygen in the creek system has collapsed this month, plummeting to 2.8 milligrams per liter — well into lethal stress for most aquatic invertebrates. Whether the larva that became this adult found a cleaner refuge upstream, or simply experienced milder conditions before the freefall, remains unknown. What is clear is that the broader dragonfly community — Widow Skimmers, Common Green Darners, Blue Dashers, and a dozen other species active in the parks and ponds along the Platte — reminds us how much ecological work these urban water bodies still perform. Even as the river itself teeters, they hold.

Dissolved oxygen dropped to 3.6 mg/L today—the lowest reading yet this month, sliding further below the already worrying 3.9 recorded just five days ago. A sudden flow pulse brought 35 cubic feet per second through the creek, a seven-fold spike from the sluggish 5-foot-per-second average that has prevailed for two weeks. But the pulse arrived far too late: midsummer thermal loading has run so deep that one surge of cooler water cannot reverse it.Speckled Duns (Callibaetis spp.) have been holding steady throughout the area all month—sightings from late June into early July across the lower reaches. These mayflies thrive in moderate flow and good oxygenation; their presence here now underscores what these collapsing conditions are working against. Water temperature climbed to 20.6°C, and while pH remains neutral at 7.5, the oxygen deficit alone threatens the cold-water invertebrate community that has persisted through drought and low flow.

This morning's water sample registered 3.9 mg/L of dissolved oxygen — below the stress threshold for aquatic life. On a stream that has nearly stopped flowing in the July heat, the chemistry is working against everything that lives in it.Warm water simply cannot hold as much oxygen as cool water does, and low flow concentrates nutrients rather than flushing them downstream. That one-two punch arrives at a particularly vulnerable moment: seven water bodies within five miles are already federally listed as impaired. The margin for error on this stream is very thin.

Clear Creek is running at a near-trickle in late June — weeks ahead of the seasonal low-flow period, and at flows that concentrate both heat and pollutants in a stream already federally listed as impaired. The creek sits in the grip of a hydrological pattern 160 years in the making, traced directly to upstream diversions that began during the Gold Rush and have persisted ever since.Current streamflow is 0.38 cubic feet per second, a stark reminder that the damage done to western waterways compounds across generations. Low flows warm the water and reduce its capacity to dilute agricultural runoff, mine seepage, and urban inputs — a cascade that regulatory agencies acknowledge through the federal impairment designation and the requirement for a total maximum daily load study. The stress on aquatic life is not accidental; it is the legacy of water extraction decisions made in the 1800s, still playing out in the 21st century.

Along the open edges and disturbed meadows near Westminster, the wild bergamot is finishing its bloom cycle. Some plants still carry a fringe of pale lavender flowers, but most heads have gone to seed — the tight, bristled clusters drying in place on stiff upright stems. This is the window that matters for American goldfinches, and right now they are using it.Wild bergamot is a native mint-family plant, and it grows in dense stands where the soil is dry and the sun is full. It flowers through mid-summer, attracting golden northern bumble bees, two-tailed swallowtails, and a steady rotation of other pollinators. But once pollination is done, the plant shifts its investment. Each spent flower head develops into a cluster of small, dry nutlets packed tightly inside the dried calyx. To a goldfinch, that structure is a seed cache. The bird lands directly on the stem, grips the head with its feet, and works the seeds out with its bill, one by one. If you are near a bergamot stand right now, watch for the stems swaying without wind. That motion is almost always a goldfinch.American goldfinches are one of the latest-nesting songbirds in North America. Most songbirds time their breeding to coincide with the peak of insect abundance in late spring. Goldfinches do something different: they wait for thistles, bergamot, and other composite and mint-family plants to set seed before they begin nesting. The female lines her nest almost exclusively with plant down, often from thistle and milkweed, and the nestlings are fed a diet of regurgitated seeds rather than insects. That dependency on seed maturity pushes their nesting peak into the heart of summer, which is exactly where we are now. The showy milkweed nearby is already producing pods, and the goldfinches will use that too, both for nest material and eventually for food. The plant community here is giving them everything they need at the same time.Male goldfinches are in their brightest plumage through the breeding season: a sharp, saturated yellow with black wings and a black cap. That color comes from carotenoid pigments the birds cannot produce themselves. They get it from the seeds and plant matter they eat, particularly the yellow-pigmented compounds in certain flowers and seed oils. A male that has fed well on a diverse seed diet through the spring carries more pigment into his feathers during the summer molt. The brightness you see on a goldfinch working a bergamot head is, in a direct way, a record of what that bird has been eating for the past several months.The bergamot stands here also carry other visitors worth noting. The golden northern bumble bee, which is a threatened species in this region, works the remaining open flowers with a focused persistence. The plains bee assassin, a native ambush predator, sometimes waits motionless on flower heads for exactly that kind of visitor. Both species are present in this area, and both are tied to the bergamot in different ways: one as a pollinator, one as a predator of pollinators. The goldfinch, arriving weeks later for the seeds, is using a resource the plant produced partly because those earlier visitors did their work.The bergamot stems stand about waist high in full sun. If you are near a patch of them, look at the dried heads. Many will show small gaps where seeds have already been taken. Some stems will still be moving. The goldfinch's call is a bright, ascending note, often given in flight — four or five syllables that rise and then fall. In the heat of a peak summer afternoon, with the milkweed blooming and the bergamot going to seed, that call is one of the more reliable sounds in this landscape.

Both showy milkweed and butterfly milkweed opened their flowers this week, marking the start of peak nectar season on the Front Range. These plants are critical refueling stops for monarchs in migration, and their reliable bloom timing anchors the pulse of the entire prairie ecosystem through early summer.Two-tailed Swallowtails have been active along the corridor — four sightings in the past two months confirm the broader butterfly migration is in motion. The landscape is waking up.Water quality remains a shadow over this seasonal renewal. Ralston Creek below continues to carry a pollution burden that triggered federal impairment designation; its cleanup plan remains pending, with no timeline set. For now, the flowering and the insects are thriving — but the stream that once powered this grassland sits on hold.

The air carries a sweet weight near Westminster's open spaces, where clusters of pink and orange flowers rise from the grassland. Showy milkweed stands tall with broad leaves and dome-shaped flower heads, each bloom a dusty rose color. Nearby, butterfly milkweed spreads lower to the ground, its flowers burning bright orange in the summer heat. Both plants have opened their complex flowers just as the Golden Northern Bumble Bee reaches peak activity in its breeding season.The Golden Northern Bumble Bee works these milkweed flowers with deliberate intensity. She lands heavily on a flower cluster, her golden-yellow body contrasting with the pink petals of showy milkweed. Each milkweed flower presents a challenge. The pollen sits trapped in small sacs that must be triggered to release their contents. The bee grips the flower and vibrates her flight muscles without flying, a behavior called buzz pollination. The vibration shakes loose the pollen packets, which attach to her legs and body as waxy yellow masses. She moves methodically from flower to flower, collecting both nectar and pollen while inadvertently transferring genetic material between plants.This relationship sustains both species through summer's demands. The Golden Northern Bumble Bee, threatened throughout its range, depends on diverse flower resources to feed her growing colony. Queen bees emerged from winter hibernation in spring and have spent weeks establishing underground nests. Now their worker daughters forage constantly to support developing larvae back in the colony. Milkweed provides high-quality protein from its pollen and concentrated sugars from its nectar. The timing aligns perfectly with the colony's peak growth period, when dozens of workers need fuel for constant foraging trips. For the milkweeds, these bees serve as essential pollinators. The plants' complex flower structure evolved specifically to ensure that visiting insects pick up and transfer pollen effectively. Without pollinators like bumble bees, milkweed populations cannot produce the seeds that will become next year's plants. Each successful pollination leads to the formation of the distinctive pointed pods that will split open in autumn, releasing seeds on silky white plumes.Other native bees and butterflies also visit these blooming milkweeds, but the Golden Northern Bumble Bee's size and strength make it particularly effective at working the flowers' intricate mechanisms. Two-tailed Swallowtails and Orange Sulphurs flutter between the orange butterfly milkweed blooms, their long tongues reaching deep for nectar. The invasive Western Honey Bee also forages here, though it often steals nectar by biting holes in flower bases rather than entering through the proper channels that ensure pollination. The native bees remain the more reliable partners in this ancient exchange between plant and pollinator. Walk quietly among these flowering patches and you can hear the steady hum of working bees, their flight muscles generating the vibrations that unlock each flower's hidden rewards.

The gravel along the Westminster trail crunches underfoot, each step announcing your presence to every creature within earshot. In late spring, this seemingly barren stretch between the canal and the open fields becomes a theater of deception. The killdeer have chosen this harsh landscape for their most vulnerable act: raising young on the open ground.A killdeer nest is barely a nest at all. Four speckled eggs rest in a shallow scrape, sometimes lined with a few pebbles or bits of dried grass, sometimes holding nothing but the eggs themselves against the earth. The birds select parking lots, gravel paths, baseball diamonds, and construction sites. They choose exposure over shelter, trusting in camouflage and performance over concealment. The eggs blend so perfectly with their surroundings that you could walk within arm's length and see nothing but stones.When a killdeer detects a threat near its nest, it launches into one of the most convincing performances in the bird world. The adult bird moves away from the nest site, dragging one wing as if broken, calling in distress, stumbling forward just close enough to hold your attention. The broken wing display pulls predators and people alike away from the hidden eggs. The bird stays just out of reach, always moving farther from the nest, maintaining the illusion of an easy meal until the threat has moved a safe distance away. Then the wing heals instantly. The killdeer takes flight, circles back, and settles near its eggs as if nothing happened. This deception works on foxes, dogs, children, and adults who have seen it dozens of times but still find themselves following the apparently injured bird.The killdeer's choice of nesting habitat reflects a calculated risk. Ground nests face constant danger from predators, weather, and human activity. But open ground offers advantages that dense cover cannot. The adult birds can spot approaching threats from a distance. They have room to perform their distraction displays. The eggs receive direct warmth from the sun, reducing the time adults must spend incubating. When the chicks hatch, they can run within hours, following their parents to feeding areas where insects gather in the short grass and muddy edges of the canal.During late spring in Westminster, the killdeer work the edges where water meets land. They probe the soft mud for invertebrates, their bills moving quickly and precisely. The chicks, covered in downy feathers that match the mottled ground, follow close behind their parents, learning to find food in the narrow zone between the flowing water and the dry earth. Their legs appear too long for their bodies, but those legs carry them quickly across uneven ground and through shallow water where aquatic insects emerge in increasing numbers as the season warms.The killdeer's survival strategy depends on this landscape remaining open and disturbed. They need the bare ground that other birds avoid. Construction sites, mowed fields, and graveled areas provide the habitat where their camouflage works best. In Westminster, they find these conditions along the canal trails, in the margins between developed areas and open space, in places where human activity has created the scattered stones and short vegetation that killdeer require.Step quietly along the trail now and listen for the sharp call that gives this bird its name. If you hear it, stop and look carefully at the ground around you. Somewhere within fifty feet, four spotted eggs rest in a scrape so shallow it barely interrupts the surface of the earth. The parent bird may be watching you, ready to begin its performance if you venture too close. The warm air carries the scent of new growth from the canal-side vegetation, and the late spring light illuminates each piece of gravel with equal clarity, making the hidden eggs invisible among ten thousand stones that look exactly like them.

The morning air holds the cool of late spring in Park Hill, where cottonwoods spread their new leaves and willows release clouds of pollen. Step outside if you can. Close your eyes and listen for the sound that cuts through the bird chorus: a metallic trill, sharp and insistent, followed by silence.That trill belongs to a Broad-tailed Hummingbird (Selasphorus platycercus), and the silence is the bird hovering. Right now, as May deepens toward June, these hummingbirds are establishing territories and beginning to nest. The males arrived first from their wintering grounds in Mexico, staking out the best feeding spots. The females followed, evaluating both mates and real estate. What they both seek, urgently, are the tubular purple flowers of Broadbeard Beardtongue (Penstemon angustifolius). These native wildflowers bloom in tight synchrony with the hummingbirds' arrival, their peak flowering timed to fuel the birds' most energy-intensive season.The beardtongue opens its flowers in clusters along tall stems, each bloom a perfect fit for a hummingbird's bill and tongue. The flower's architecture excludes most other visitors. Bees cannot reach the nectar at the base of the long tube. Butterflies lack the hovering precision the narrow opening demands. But a Broad-tailed Hummingbird approaches each flower like a key finding its lock. The bird inserts its needle-thin bill deep into the tube, its forked tongue flicking out to lap nectar from the base. As it feeds, pollen dusts the crown of its head and the base of its throat. When the hummingbird visits the next beardtongue, that pollen transfers, completing the exchange that has sustained both species across thousands of springs.This partnership operates on precision timing. The beardtongue cannot afford to bloom too early, when late frosts might kill the flowers, or too late, when the hummingbirds have already committed to other nectar sources. The hummingbirds cannot arrive before their primary fuel appears, but they also cannot wait too long, or the best nesting sites will be taken by competitors. Female Broad-tailed Hummingbirds are building their nests now, gathering spider silk and plant down, shaping cups barely larger than a walnut. Each nest represents thousands of trips to beardtongue flowers, each feeding bout converting nectar into the energy needed to incubate eggs and feed young. The beardtongue, in turn, depends on this intensive visitation. Other pollinators visit sporadically, but hummingbirds work systematically, moving from flower to flower within a patch, then traveling between patches, ensuring genetic diversity in the plant's reproduction.Look for the beardtongue in open areas where the soil drains well, its purple spikes rising above shorter grasses. Listen for the hummingbird's trill, often heard before the bird is seen. If you spot the flash of metallic green and the ruby throat of a male, watch how it moves between flowers. The feeding is methodical, efficient, each visit lasting only seconds before the bird moves on. The sound of its wings shifts as it hovers, a higher pitch than the trill of its territorial call, steady as a small motor running in the morning air.

The cottonwoods along Denver's urban waterways have pushed out their first broad leaves, and the switchgrass sends up new shoots through last year's weathered stems. In the open ground between water and woodland, where gravel meets grass and human paths cross animal trails, the killdeer (Charadrius vociferus) stakes its claim to the season's most exposed real estate.This plover builds no nest. The female scrapes a shallow depression in bare soil or sparse grass, sometimes lined with a few pebbles or bits of debris, and settles her four buff-colored eggs directly on the ground. The eggs blend so perfectly with their surroundings that even a careful observer can walk within feet without seeing them. What you cannot miss is the parent bird's response to your presence. The killdeer launches into one of nature's most convincing performances: dragging a wing as if broken, calling in apparent distress, leading you away from the nest site with every appearance of vulnerability. This broken-wing display draws potential predators toward what seems like easy prey, while the eggs remain hidden in their shallow scrape dozens of yards behind.The deception works because it exploits a predator's instinct to pursue the easiest target. A fox, hawk, or curious human follows the seemingly injured bird, which stays just out of reach, wing dragging pitifully. Once the threat has been led far enough from the nest, the killdeer miraculously recovers, flies strongly back toward its territory, and resumes normal foraging behavior. The performance is so convincing that even experienced birders find themselves momentarily concerned for the bird's welfare. But this is calculated theater, refined over thousands of generations of ground-nesting survival.Killdeer choose these marginal spaces because they offer both advantages and challenges that other birds cannot navigate. The open ground provides clear sightlines for spotting approaching danger, while the sparse vegetation offers just enough cover for camouflaged eggs. These edges between habitats attract the insects that killdeer feed on: beetles, grasshoppers, and fly larvae that thrive where soil meets grass meets water. The birds probe and pick through the earth with quick, precise movements, their long legs allowing them to wade through shallow puddles and navigate uneven terrain. During this nesting season, both parents share territory defense and chick-rearing duties, though only the adult performing the distraction display will risk everything to protect the clutch.If you find yourself walking these transitional spaces where pavement gives way to prairie, where storm runoff creates temporary wetlands, listen for the killdeer's namesake call echoing across the open ground. The sound carries farther than you might expect, a clear announcement of presence and territory that cuts through the morning air. Watch for the flash of white on dark wings as the bird moves between feeding and guarding, and notice how it chooses the most exposed, seemingly vulnerable spots to make its stand.