BirdAnalyst
Species · BCR 9 · BBS 2026 Release · 1966–2025

Marsh Wren In Great Basin

All regionsGreat BasinForest birds

Marsh Wren in Great Basin has surged: up 584% on the route-weighted index since 1971.

+584%Since 1971TrendPercent 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 →
76Routes 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 →

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 Great Basin: up 584% on the route-weighted index since 1971.

Marsh Wren In Great Basin Population Forecast

If the recent trend holds, Marsh Wren in Great Basin is projected to rise about 177% by 2030 — from 0.54 in 2025 to a central estimate of 1.5 (95% range 0.12–2.9). A 5-year backtest shows a typical error of ±204.9%, with 40% of held-out values landing inside the 95% band.

+177%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 →
1.5Projected 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 →
0.12–2.995% 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 →
±204.9%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 Great Basin is projected to rise about 177% by 2030 — from 0.54 in 2025 to a central estimate of 1.5 (95% range 0.12–2.9). A 5-year backtest shows a typical error of ±204.9%, with 40% 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 →
20261.50.092.8
20271.50.102.8
20281.50.112.9
20291.50.122.9
20301.50.122.9

Routes In Great Basin

Routes recording Marsh Wren in Great Basin.
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 →
DorrisCALIFORNIA762019
ReardanWASHINGTON192014
MerrillOREGON132022
Bear RiverUTAH122025
LikelyCALIFORNIA112025
Fish LakeOREGON112025
PrincetonOREGON91985
CallaoUTAH82025
Honey LakeCALIFORNIA62025
Daniels ResIDAHO52025
ChinchaloOREGON52025
GardnervilleNEVADA42011
UmatillaOREGON42023
Malheur NwrOREGON41998
BrewsterWASHINGTON42015
ArdenvoirWASHINGTON41968
TonasketWASHINGTON42010
Iron GateCALIFORNIA31992
SpringfieldIDAHO32018
RanchograndeNEVADA32008
Virgin CreekNEVADA32015
Blizzard GapOREGON32025
EwanWASHINGTON32019
PotholesWASHINGTON32023
NubieberCALIFORNIA22018

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