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Species · BCR 12 · BBS 2025 Release · 1966–2024

Marsh Wren In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Marsh Wren in Boreal Hardwood Transition has surged: up 206% on the route-weighted index since 1970.

+206%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 →
37Routes 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 →
52YearsYears 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 Boreal Hardwood Transition: up 206% on the route-weighted index since 1970.

Marsh Wren In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Marsh Wren in Boreal Hardwood Transition is projected to rise about 39% by 2029 — from 0.16 in 2024 to a central estimate of 0.22 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±64.1%, with 100% of held-out values landing inside the 95% band.

+39%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 →
0.22Projected 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 →
0.00–0.6195% 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 →
±64.1%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, Marsh Wren in Boreal Hardwood Transition is projected to rise about 39% by 2029 — from 0.16 in 2024 to a central estimate of 0.22 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±64.1%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.220.000.61
20260.220.000.61
20270.220.000.61
20280.220.000.61
20290.220.000.61

Routes In Boreal Hardwood Transition

Routes recording Marsh Wren in Boreal Hardwood Transition.
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 →
Little ForkMINNESOTA121990
CohassetMINNESOTA111990
BackusMINNESOTA52024
Iron RiverWISCONSIN52024
BayfieldWISCONSIN51982
DebsMINNESOTA22023
BrainerdMINNESOTA22023
GreenbushMINNESOTA22023
MareniscoMICHIGAN12015
Brocky LakeMICHIGAN12013
GilchristMICHIGAN11995
Skegemog PtMICHIGAN12011
Seney NwrMICHIGAN11996
Wigwam BayMINNESOTA12018
Mille LacsMINNESOTA12016
Pine RiverMINNESOTA12024
HovlandMINNESOTA11983
Sherry LakeMINNESOTA11987
BemidjiMINNESOTA11968
WaskishMINNESOTA12008
MahtowaMINNESOTA12015
McgregorMINNESOTA12008
BlackduckMINNESOTA12019
GlendaleMINNESOTA12016
Red LakeMINNESOTA12022

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