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Species · Arizona · BBS 2025 Release · 1966–2024

Williamson's Sapsucker Population Trend in Arizona

All statesForest birds

Williamson's Sapsucker in Arizona has surged: up 162% on the route-weighted index since 1985.

+162%Since 1985TrendPercent 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 →
10Routes 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 →
34YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Williamson's Sapsucker Trends in ArizonaNotable 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 →

Williamson's Sapsucker has surged in Arizona: up 162% on the route-weighted index since 1985.

Williamson's Sapsucker Population Forecast in Arizona

If the recent trend holds, Williamson's Sapsucker in Arizona is projected to stay roughly flat through 2029, near 0.14 (95% range 0.00–0.32). A 5-year backtest shows a typical error of ±91.2%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.14Projected 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 →
0.00–0.3295% 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 →
±91.2%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, Williamson's Sapsucker in Arizona is projected to stay roughly flat through 2029, near 0.14 (95% range 0.00–0.32). A 5-year backtest shows a typical error of ±91.2%, with 80% of held-out values landing inside the 95% band.19742029
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 →
20250.140.000.31
20260.140.000.31
20270.140.000.31
20280.140.000.31
20290.140.000.32

Williamson's Sapsucker Survey Routes in Arizona

Routes recording Williamson's Sapsucker in Arizona.
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 →
Tsaile620231993
Sawmill220062005
Sprucedale220191994
Forest Lakes119941994
Pinetop120222022
Flagstaff119941988
Alpine120231995
Happy Jack119771977
Dry Park120241992
Blue119851974

Williamson's Sapsucker Population Trend in Other States

californiacoloradoidahomontananevadanew-mexicooregonutahwashingtonwyoming

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