BirdAnalyst
Species · Washington · BBS 2025 Release · 1966–2024

Swainson's Hawk Population Trend in Washington

All statesGeneralists

Swainson's Hawk in Washington has surged: up 208% on the route-weighted index since 1971.

+208%Since 1971TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
40Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Swainson's Hawk Trends in WashingtonNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Swainson's Hawk has surged in Washington: up 207% on the route-weighted index since 1971.

Swainson's Hawk Population Forecast in Washington

If the recent trend holds, Swainson's Hawk in Washington is projected to rise about 36% by 2029 — from 0.37 in 2024 to a central estimate of 0.50 (95% range 0.30–0.70). A 5-year backtest shows a typical error of ±96.1%, with 60% of held-out values landing inside the 95% band.

+36%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.50Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.30–0.7095% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±96.1%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Swainson's Hawk in Washington is projected to rise about 36% by 2029 — from 0.37 in 2024 to a central estimate of 0.50 (95% range 0.30–0.70). A 5-year backtest shows a typical error of ±96.1%, with 60% of held-out values landing inside the 95% band.19682029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20250.470.280.67
20260.480.280.68
20270.490.290.69
20280.490.300.69
20290.500.300.70

Swainson's Hawk Survey Routes in Washington

Routes recording Swainson's Hawk in Washington.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Keystone820241994
Columbia Nwr620221996
Sulphur520221995
Hatton519941992
Richland420242006
Moses Lake320221974
Snowden319841982
Hartline320221995
Horn Rapids320242005
Selah220162002
Ewan 2220232023
Harrington220121973
Connell220151968
Bickleton220041982
Ewan220091989
Scootney Reservoir220242009
Potholes220191996
Moses Coulee220211993
Odessa220241993
Yakima220022002
Hanford Site119961988
Arid Land Er119961988
Brewster119851977
Wapato119721972
Mercer120211969

Swainson's Hawk Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.