BirdAnalyst
Species · BCR 13 · BBS 2025 Release · 1966–2024

Purple Martin In Lower Great Lakes / St. Lawrence Plain

All regionsLower Great Lakes / St. Lawrence PlainAerial insectivores

Purple Martin in Lower Great Lakes / St. Lawrence Plain has declined: down 31% on the route-weighted index since 1968.

-31%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 →
71Routes 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 →

No notable trend signals for Purple Martin in Lower Great Lakes / St. Lawrence Plain. See the full index history below.

Purple Martin In Lower Great Lakes / St. Lawrence Plain Population Forecast

If the recent trend holds, Purple Martin in Lower Great Lakes / St. Lawrence Plain is projected to stay roughly flat through 2029, near 1.4 (95% range 0.01–2.7). A 5-year backtest shows a typical error of ±25.2%, with 100% of held-out values landing inside the 95% band.

-9%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 →
1.4Projected 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 →
0.01–2.795% 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 →
±25.2%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 Lower Great Lakes / St. Lawrence Plain is projected to stay roughly flat through 2029, near 1.4 (95% range 0.01–2.7). A 5-year backtest shows a typical error of ±25.2%, with 100% 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 →
20251.40.082.8
20261.40.062.8
20271.40.042.8
20281.40.032.8
20291.40.012.7

Routes In Lower Great Lakes / St. Lawrence Plain

Routes recording Purple Martin in Lower Great Lakes / St. Lawrence Plain.
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 →
Sugar GrovePENNSYLVANIA282024
RandolphNEW-YORK242017
LattasburgOHIO132024
HarmonsburgPENNSYLVANIA132023
West SenecaNEW-YORK121973
Grand IsleVERMONT121998
MacdougallNEW-YORK82023
PittsfieldOHIO72024
TeeplevillePENNSYLVANIA72024
DuanesburgNEW-YORK61989
NashvilleNEW-YORK62018
WatertownNEW-YORK61987
NaplesNEW-YORK62024
AkeleyPENNSYLVANIA61976
WillsboroNEW-YORK51980
PhiladelphiaNEW-YORK52012
Oriskany FlsNEW-YORK41967
Canadice LNEW-YORK42024
Mt MorrisNEW-YORK41979
Cherry HillNEW-YORK41981
PeruOHIO41978
Herner CrnsOHIO42024
E YoungstownNEW-YORK32019
PulaskiNEW-YORK31988
OneidaNEW-YORK31980

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