Amphibians

Cascades Frog

Rana cascadae · also called Cascades frog

Near Threatened ↓ insectivorecarnivore Mountains Rivers & wetlands Temperate forest

A Cascades frog lives its whole life to the rhythm of the mountain thaw. It emerges as the ice breaks up, moves straight to the first meltwater pool — often still ringed with snow — and lays its eggs in water barely above freezing, betting that the short alpine summer will be long enough for the tadpoles to finish. Across the southern half of its range, that bet has been overwhelmed by stocked trout and disease, and the frog is gone.

Overview

The Cascades frog, Rana cascadae, is a high-country frog of the US Pacific Northwest — the Cascade Range from Washington to northern California, plus the Olympic and Klamath mountains, mostly between about 600 and 2,700 m. Adults live in and around wet meadows, bogs, tarns, and slow headwater streams, rarely far from water, and eat insects and other small invertebrates.

Breeding at the snow line

Cascades frogs begin spawning within days of the ice melting, sometimes in water a couple of degrees above freezing. Because the alpine summer is short, the tadpoles must hatch, grow, and transform in one season, and an early frost or a dry year can wipe out a whole cohort.

A collapse in the south

Once abundant range-wide, the Cascades frog has vanished from its entire southern range, including the Lassen region of northern California. The chief cause is trout stocked into naturally fishless mountain lakes, which eat tadpoles and compete for food — and removing those trout has been shown to let the frogs recover. Working alongside it are the chytrid fungus, pesticide drift from the Central Valley, disease outbreaks, drought, and past cattle grazing.

Status

Near Threatened and decreasing. The California populations have collapsed and are the subject of Endangered Species Act petitions; the species is patchier but more secure in the Oregon and Washington Cascades and the Olympics. Its dependence on cold, clean, fishless water with a reliable snowpack leaves it very exposed to a warming climate.

Cascades Frog: common questions

Where does the Cascades frog live?

Only in the mountains of the Pacific Northwest of the United States. Its core range is the Cascade Range from northern Washington through Oregon into northern California, plus the Olympic Mountains of Washington and the Klamath and Trinity mountains of northwestern California. It is a mid to high elevation animal, most common from about 800 metres up to the treeline and a bit beyond, in wet meadows, bogs, pond and lake margins, and slow headwater streams within conifer forest and subalpine country. It is essentially absent from the lowlands, where it is replaced by other frogs.

Why has the Cascades frog disappeared from northern California?

A combination of pressures that hit the southern, warmer, drier edge of the range hardest. The stocking of trout into naturally fishless high lakes removed a large share of the frog's safe breeding water. The amphibian chytrid fungus arrived and caused die-offs. Pesticides and other chemicals used in California's Central Valley drift up on the wind and are deposited in the Sierra and southern Cascade snowpack and water, adding chronic stress. Drought and reduced snowpack from a warming climate shrink and dry the breeding pools. Historic livestock grazing degraded the meadows the frog depends on. Together these drove the species out of the Lassen area and most of its former California range, and the surviving California populations are now the subject of Endangered Species Act petitions.

Can the Cascades frog be helped, and is removing fish effective?

Yes, and fish removal is one of the clearest success stories. Studies in the Cascades and in the neighbouring Sierra Nevada, where a close relative faces the same problem, have shown that when introduced trout are removed from selected high lakes, either by netting or by simply ending stocking and letting the fish die out, mountain frog populations rebound within several years as tadpoles survive again. Land managers now leave many high lakes fishless or restore them, protect and rehabilitate wet meadows, monitor for chytrid, and factor amphibians into snowpack and water decisions. The harder problems, chytrid and a warming, drying climate, have no quick fix.

How does a frog breed in near-freezing water?

Cascades frogs and other high-elevation frogs are adapted to a very cold, very short breeding window. Adults emerge from overwintering as soon as the ice begins to break up and move immediately to the first available open water, which may still be ringed with snow and only one or two degrees above freezing. They lay their eggs in the shallowest, sunniest spot, often in a communal mass with other pairs, because the dark egg jelly absorbs sunlight and the shallow water warms fastest during the day. The embryos and tadpoles are cold-tolerant and develop as the water warms through the summer, racing to complete metamorphosis before autumn. It is a high-risk strategy that fails in years with a late frost or an early freeze.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published September 10, 2026. Last updated September 10, 2026.

Quick facts

Scientific name: Rana cascadae
Diet: Insects and other small invertebrates snapped up along the edges of ponds and streams and in wet meadows, including beetles, flies, ants, spiders, and terrestrial and aquatic bugs, with the tadpoles grazing algae and biofilm in the cold breeding pools
It breeds at the snow line: Cascades frogs are high-country specialists, and they begin breeding within days of the ice melting from a pool, often laying their eggs in water only a few degrees above freezing and sometimes surrounded by snow, so the whole population is tied to the timing of the mountain thaw
A short season and a fast tadpole: Because the alpine summer is brief, Cascades frog tadpoles must hatch, grow, and transform in a single season before the pools freeze or dry, and eggs or larvae caught by an early frost or a dry year can be lost entirely
Tied to meadows and shallow water: Adults live in and around wet meadows, seeps, bogs, tarns, and slow headwater streams from the middle elevations up to and past the treeline, rarely straying far from water, and they overwinter underwater or in wet ground below the frost
A textbook mountain-amphibian decline: The Cascades frog was once abundant throughout its range, but it has disappeared from the entire southern portion, including the Lassen region of northern California where it was formerly common, and it has declined in parts of Oregon, making it one of the standard case studies of amphibian loss in western North America
Trout are a major cause: High mountain lakes are naturally fishless, and the widespread stocking of trout for recreational angling put a new predator into the frog's breeding waters that eats tadpoles and small frogs and competes with them for insects, and removing trout from key lakes has been shown to let Cascades frogs recover
Several pressures acting together: Alongside introduced fish, the species is hit by the amphibian chytrid fungus, by pesticides and other airborne chemicals that drift up from the agricultural valleys and settle in mountain water and snow, by disease outbreaks, by drought linked to a warming climate, and historically by cattle grazing that damaged the meadows
Range: The mountains of the Pacific Northwest of the United States, from the North Cascades of Washington south through the Oregon Cascades to the Klamath Mountains and the southern Cascades and Trinity Alps of northern California, plus the Olympic Mountains, generally between about 600 and 2700 m elevation in and around ponds, lakes, meadows, bogs, and slow streams within coniferous forest and subalpine parkland.
Conservation status: Near Threatened ↓ ≈ The Cascades frog is listed as Near Threatened and declining, with the range-wide population reduced and the southern populations in California considered a distinct segment that has collapsed, prompting petitions for protection under the US Endangered Species Act. It remains reasonably secure in parts of the Cascades of Oregon and Washington and in the Olympic Mountains, but even there it is patchy, and its dependence on cold, clean, fishless mountain water with a reliable snowpack makes it especially exposed to climate warming in the wild