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Species · Arizona · BBS 2025 Release · 1966–2024

Blue-throated Mountain-gem Population Trend in Arizona

All statesGeneralists

Blue-throated Mountain-gem in Arizona has fallen sharply: down 50% on the route-weighted index since 1979.

-50%Since 1979TrendPercent 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 →
5Routes 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 →
30YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Blue-throated Mountain-gem 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 declinecomputed 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 →

Blue-throated Mountain-gem has fallen sharply in Arizona: down 50% on the route-weighted index since 1979.

Blue-throated Mountain-gem Population Forecast in Arizona

If the recent trend holds, Blue-throated Mountain-gem in Arizona is projected to fall about 64% by 2029 — from 0.09 in 2024 to a central estimate of 0.03 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±46.9%, with 100% of held-out values landing inside the 95% band.

-64%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 →
0.03Projected 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 →
0.00–0.1395% 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 →
±46.9%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, Blue-throated Mountain-gem in Arizona is projected to fall about 64% by 2029 — from 0.09 in 2024 to a central estimate of 0.03 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±46.9%, with 100% of held-out values landing inside the 95% band.19772029
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 →
20250.040.000.13
20260.030.000.13
20270.030.000.13
20280.030.000.13
20290.030.000.13

Blue-throated Mountain-gem Survey Routes in Arizona

Routes recording Blue-throated Mountain-gem 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 →
Portal320241977
Rucker120081993
Sunizona 2120152015
Mcneal119971997
Peña Blanca120012001

Blue-throated Mountain-gem Population Trend in Other States

texas

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