BirdAnalyst
Species · BCR 24 · BBS 2026 Release · 1966–2025

Purple Martin In Central Hardwoods

All regionsCentral HardwoodsAerial insectivores

Purple Martin in Central Hardwoods has surged: up 142% on the route-weighted index since 1968.

+142%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 →
164Routes 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 →
59YearsYears 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 →

Purple Martin has surged in Central Hardwoods: up 142% on the route-weighted index since 1968.

Purple Martin In Central Hardwoods Population Forecast

If the recent trend holds, Purple Martin in Central Hardwoods is projected to fall about 17% by 2030 — from 11 in 2025 to a central estimate of 9.0 (95% range 6.5–12). A 5-year backtest shows a typical error of ±15.3%, with 100% of held-out values landing inside the 95% band.

-17%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 →
9.0Projected 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 →
6.5–1295% 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 →
±15.3%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 Central Hardwoods is projected to fall about 17% by 2030 — from 11 in 2025 to a central estimate of 9.0 (95% range 6.5–12). A 5-year backtest shows a typical error of ±15.3%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20268.86.311
20278.96.311
20288.96.411
20299.06.511
20309.06.512

Routes In Central Hardwoods

Routes recording Purple Martin in Central Hardwoods.
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 →
GranitevilleMISSOURI912025
AkersMISSOURI582025
SyracuseMISSOURI582024
New PhilaINDIANA442025
Sewell ShopKENTUCKY392025
KeysburgKENTUCKY372025
PeytonsvilleTENNESSEE362025
DelwoodILLINOIS282025
Indian SpgsINDIANA282025
PlumKENTUCKY282025
ColcordOKLAHOMA272022
FarwellARKANSAS262018
MillerMISSOURI232025
Valhermoso SpgsALABAMA222010
East UnionKENTUCKY222025
BremenILLINOIS212025
DrakesboroKENTUCKY212003
CollinwoodTENNESSEE212025
WashingtonINDIANA202025
NewberryINDIANA202025
Doe RunMISSOURI202025
GlencoeKENTUCKY192018
WhitewaterMISSOURI192025
SwaimALABAMA182025
GlenTENNESSEE182025

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