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

Purple Martin In Northern Rockies

All regionsNorthern RockiesAerial insectivores

Purple Martin in Northern Rockies has declined: down 44% on the route-weighted index since 1998.

-44%Since 1998TrendPercent 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 RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
21YearsYears 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 Purple Martin in Northern Rockies. See the full index history below.

Forecast

If the recent trend holds, Purple Martin in Northern Rockies is projected to stay roughly flat through 2028, near 0.02 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±33.5%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2028TrendPercent 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 →
0.02Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1095% 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 →
±33.5%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, Purple Martin in Northern Rockies is projected to stay roughly flat through 2028, near 0.02 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±33.5%, with 100% of held-out values landing inside the 95% band.19682028
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 →
20240.030.000.10
20250.030.000.10
20260.030.000.10
20270.020.000.10
20280.020.000.10

Routes In Northern Rockies

Routes recording Purple Martin 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 →
Saleratus CrUTAH82004
WoodruffUTAH42022
Savery 2WYOMING42022
St MaryMONTANA31968
LayCOLORADO22023

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