BirdAnalyst
Species · BCR 18 · BBS 2025 Release · 1966–2024

Purple Martin In Shortgrass Prairie

All regionsShortgrass PrairieAerial insectivores

Purple Martin in Shortgrass Prairie has collapsed: down 80% on the route-weighted index since 1977.

-80%Since 1977TrendPercent 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 →
13Routes 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 →
30YearsYears 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 Shortgrass Prairie: down 80% on the route-weighted index since 1977.

Forecast

If the recent trend holds, Purple Martin in Shortgrass Prairie is projected to fall about 53% by 2029 — from 0.11 in 2024 to a central estimate of 0.05 (95% range 0.00–0.37). A 5-year backtest shows a typical error of ±77.6%, with 100% of held-out values landing inside the 95% band.

-53%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 →
0.05Projected 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 →
0.00–0.3795% 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 →
±77.6%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 Shortgrass Prairie is projected to fall about 53% by 2029 — from 0.11 in 2024 to a central estimate of 0.05 (95% range 0.00–0.37). A 5-year backtest shows a typical error of ±77.6%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20250.060.000.38
20260.060.000.37
20270.060.000.37
20280.050.000.37
20290.050.000.37

Routes In Shortgrass Prairie

Routes recording Purple Martin in Shortgrass Prairie.
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 →
HardestyOKLAHOMA101972
DoughertyTEXAS82024
PostTEXAS72023
VillegreenCOLORADO41998
BethuneCOLORADO32015
PaxtonNEBRASKA31992
RankinTEXAS32018
BenkelmanNEBRASKA22022
PanhandleTEXAS22007
LoganNEW-MEXICO12017
Clear LakeOKLAHOMA12011
PantexTEXAS12024
FloydadaTEXAS12010

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