BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Black-billed Magpie In Northern Rockies

All regionsNorthern RockiesGeneralists

Black-billed Magpie in Northern Rockies has declined: down 33% on the route-weighted index since 1970.

-33%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 →
182Routes In RegionSurvey 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 SignalsNotable 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 Black-billed Magpie in Northern Rockies. See the full index history below.

Forecast

If the recent trend holds, Black-billed Magpie in Northern Rockies is projected to fall about 38% by 2029 — from 11 in 2024 to a central estimate of 6.7 (95% range 0.56–13). A 5-year backtest shows a typical error of ±38.1%, with 100% of held-out values landing inside the 95% band.

-38%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 →
6.7Projected 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 →
0.56–1395% 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 →
±38.1%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, Black-billed Magpie in Northern Rockies is projected to fall about 38% by 2029 — from 11 in 2024 to a central estimate of 6.7 (95% range 0.56–13). A 5-year backtest shows a typical error of ±38.1%, 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 →
20257.00.9013
20266.90.8213
20276.80.7313
20286.80.6413
20296.70.5613

Routes In Northern Rockies

Routes recording Black-billed Magpie in Northern Rockies.
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 →
BoulderWYOMING1122024
Clyde ParkMONTANA872024
MeeteetseWYOMING722024
CarterWYOMING682016
WoodruffUTAH562024
ChestnutMONTANA552024
Fort LoganMONTANA492024
BridgeportOREGON482022
CodyWYOMING482024
Green RiverWYOMING441984
PolsonMONTANA432024
GlenMONTANA392024
ChewelahWASHINGTON392021
Church HillMONTANA372024
Heart ButteMONTANA362024
Mtn ViewWYOMING362024
VictorMONTANA342024
SpartaOREGON332001
FontenelleWYOMING332024
LimaMONTANA322024
NewbridgeOREGON302024
RiversideWYOMING292024
Clover CreekOREGON282024
NinemileMONTANA272024
HarmonyWYOMING272023

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