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

Black-billed Magpie Population Trend in Utah

All statesGeneralists

Black-billed Magpie in Utah has fallen sharply: down 60% on the route-weighted index since 1970.

-60%Since 1970TrendPercent 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 →
90Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-billed Magpie Trends in UtahNotable 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 →

Black-billed Magpie has fallen sharply in Utah: down 60% on the route-weighted index since 1970.

Black-billed Magpie Population Forecast in Utah

If the recent trend holds, Black-billed Magpie in Utah is projected to fall about 36% by 2029 — from 5.5 in 2024 to a central estimate of 3.5 (95% range 0.00–9.0). A 5-year backtest shows a typical error of ±19.9%, with 100% 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 →
3.5Projected 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 →
0.00–9.095% 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 →
±19.9%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, Black-billed Magpie in Utah is projected to fall about 36% by 2029 — from 5.5 in 2024 to a central estimate of 3.5 (95% range 0.00–9.0). A 5-year backtest shows a typical error of ±19.9%, with 100% 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 →
20253.90.009.3
20263.80.009.2
20273.70.009.1
20283.60.009.1
20293.50.009.0

Black-billed Magpie Survey Routes in Utah

Routes recording Black-billed Magpie in Utah.
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 →
Hanna7420241997
Kamas5720241997
Woodruff5620242002
Moon Lake 22420232004
Randolph2120241992
Altonah1920151968
Hill Creek1919951993
Neponset Res1720181995
Hardware Ranch1620231994
Heber Mtn.1520242003
Promontory1420241969
Lost Cr. Res1420181995
Wellington 31320242012
Castleton1319851969
Saleratus Cr1220181995
Delta1120241987
E. Bear Lake1120221995
Wellington 21120112003
Leamington1020171992
Salt Springs920241986
Goshen920241968
Notom920241991
Gooseberry920241994
Goose Creek Mtn.820231998
Vernal820182003

Black-billed Magpie Population Trend in Other States

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