BirdAnalyst
Species · BCR 10 · BBS 2026 Release · 1966–2025

Marsh Wren In Northern Rockies

All regionsNorthern RockiesForest birds

Marsh Wren in Northern Rockies has surged: up 101% on the route-weighted index since 1973.

+101%Since 1973TrendPercent 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 →
55Routes 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 →
54YearsYears 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 →

long arc increasecomputed 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 →

Marsh Wren has surged in Northern Rockies: up 101% on the route-weighted index since 1973.

Marsh Wren In Northern Rockies Population Forecast

If the recent trend holds, Marsh Wren in Northern Rockies is projected to rise about 197% by 2030 — from 0.12 in 2025 to a central estimate of 0.34 (95% range 0.01–0.67). A 5-year backtest shows a typical error of ±49.9%, with 100% of held-out values landing inside the 95% band.

+197%Change by 2030TrendPercent 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 →
0.34Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.01–0.6795% 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 →
±49.9%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, Marsh Wren in Northern Rockies is projected to rise about 197% by 2030 — from 0.12 in 2025 to a central estimate of 0.34 (95% range 0.01–0.67). A 5-year backtest shows a typical error of ±49.9%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.330.000.66
20270.330.000.66
20280.340.010.67
20290.340.010.67
20300.340.010.67

Routes In Northern Rockies

Routes recording Marsh Wren 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 →
Seedskadee 2WYOMING102024
SeedskadeeWYOMING82023
Carter 2WYOMING82024
Willow Creek 2MONTANA72025
Neponset ResUTAH72018
MadrasOREGON32017
Ne EntranceWYOMING32024
MaybellCOLORADO22025
Browns ParkCOLORADO22025
LayCOLORADO22012
NaplesIDAHO22025
CabartonIDAHO22005
KalispellMONTANA22024
PolsonMONTANA21999
EllistonMONTANA21991
BeaverheadMONTANA22024
RandolphUTAH22024
CusickWASHINGTON22018
TensleepWYOMING22015
Green RiverWYOMING21984
CoolinIDAHO12018
Crane CreekIDAHO12003
Libby DamMONTANA11988
ArleeMONTANA12006
AugustaMONTANA12025

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.