BirdAnalyst
Species · Louisiana · BBS 2025 Release · 1966–2024

Great-tailed Grackle Population Trend in Louisiana

All statesGeneralists

Great-tailed Grackle in Louisiana has collapsed: down 90% on the route-weighted index since 1978.

-90%Since 1978TrendPercent 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 →
22Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
39YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Great-tailed Grackle Trends in LouisianaNotable 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 →

Great-tailed Grackle has collapsed in Louisiana: down 90% on the route-weighted index since 1978.

Great-tailed Grackle Population Forecast in Louisiana

If the recent trend holds, Great-tailed Grackle in Louisiana is projected to fall about 84% by 2029 — from 0.46 in 2024 to a central estimate of 0.07 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±86.7%, with 100% of held-out values landing inside the 95% band.

-84%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 →
0.07Projected 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 →
0.00–3.495% 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 →
±86.7%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, Great-tailed Grackle in Louisiana is projected to fall about 84% by 2029 — from 0.46 in 2024 to a central estimate of 0.07 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±86.7%, with 100% of held-out values landing inside the 95% band.19732029
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 →
20250.220.003.5
20260.190.003.5
20270.150.003.4
20280.110.003.4
20290.070.003.4

Great-tailed Grackle Survey Routes in Louisiana

Routes recording Great-tailed Grackle in Louisiana.
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 →
Gran Chenier14819761976
Creole9419871973
Forked Island 28120112010
Ltl Chenier 26020112010
Glencoe2320122012
Mamou819821978
Brousville620242013
River Road520242024
Port Allen520222013
Ltl Chenier520241986
De Quincy419991999
Sabine Nwr420021996
Maurice320231988
Sabine Nwr 2320172011
Hackberry120101987
Vinton 2120242023
Esther120241994
Kaplan120231998
Woodlawn120212008
Richard120231998
Forked Island120242010
Ville Platte120191994

Great-tailed Grackle Population Trend in Other States

arizonaarkansascaliforniacoloradoidahoillinoisiowakansasmissourinebraskanevadanew-mexicooklahomaoregonsouth-dakotatexasutahwyoming

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