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

Purple Martin In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionAerial insectivores

Purple Martin in Boreal Hardwood Transition has collapsed: down 98% on the route-weighted index since 1968.

-98%Since 1968TrendPercent 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 →
83Routes 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 →
58YearsYears 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 declinecomputed 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 →

Purple Martin has collapsed in Boreal Hardwood Transition: down 98% on the route-weighted index since 1968.

Purple Martin In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Purple Martin in Boreal Hardwood Transition is projected to fall about 100% by 2029 — from 0.08 in 2024 to a central estimate of 0.00 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±1384.6%, with 60% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–1.595% 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 →
±1384.6%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 Boreal Hardwood Transition is projected to fall about 100% by 2029 — from 0.08 in 2024 to a central estimate of 0.00 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±1384.6%, with 60% of held-out values landing inside the 95% band.19662029
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 →
20250.000.001.5
20260.000.001.5
20270.000.001.5
20280.000.001.5
20290.000.001.5

Routes In Boreal Hardwood Transition

Routes recording Purple Martin 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 →
BenaMINNESOTA351977
Brocky LakeMICHIGAN121980
BemidjiMINNESOTA121980
SkeelsMICHIGAN91981
Gibbs CityMICHIGAN81979
ExelandWISCONSIN71992
Crystal FlsMICHIGAN61992
CreightonMICHIGAN61980
Island LakeMINNESOTA61988
NebishMINNESOTA61995
TahquamenonMICHIGAN51980
BackusMINNESOTA51997
ShingletonMICHIGAN41981
RacoMICHIGAN41974
PickfordMICHIGAN41994
OberlinMICHIGAN41986
LudeMINNESOTA42001
Rib LakeWISCONSIN41989
CunardMICHIGAN31992
Lake CityMICHIGAN31976
Beaver LakeMICHIGAN32011
CromwellMINNESOTA32024
Wigwam BayMINNESOTA32023
McgregorMINNESOTA32022
BayfieldWISCONSIN31993

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