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Species · Arizona · BBS 2025 Release · 1966–2024

Sulphur-bellied Flycatcher Population Trend in Arizona

All statesAerial insectivores

Sulphur-bellied Flycatcher in Arizona has held roughly steady: up 4% on the route-weighted index since 1975.

+4%Since 1975TrendPercent 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 →
6Routes 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 →
44YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Sulphur-bellied Flycatcher 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 →

No notable trend signals for Sulphur-bellied Flycatcher in Arizona. See the full index history below.

Sulphur-bellied Flycatcher Population Forecast in Arizona

If the recent trend holds, Sulphur-bellied Flycatcher in Arizona is projected to fall about 41% by 2029 — from 0.11 in 2024 to a central estimate of 0.07 (95% range 0.00–0.19). A 5-year backtest shows a typical error of ±41.6%, with 100% of held-out values landing inside the 95% band.

-41%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 →
0.07Projected 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 →
0.00–0.1995% 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 →
±41.6%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, Sulphur-bellied Flycatcher in Arizona is projected to fall about 41% by 2029 — from 0.11 in 2024 to a central estimate of 0.07 (95% range 0.00–0.19). A 5-year backtest shows a typical error of ±41.6%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.070.000.20
20260.070.000.20
20270.070.000.20
20280.070.000.20
20290.070.000.19

Sulphur-bellied Flycatcher Survey Routes in Arizona

Routes recording Sulphur-bellied Flycatcher 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 →
Portal320241981
Patagonia220221970
Sunizona219781969
Rucker120091995
Sunizona 2120242012
Aztec Peak119771977

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