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Species · Louisiana · BBS 2026 Release · 1966–2025

Boat-tailed Grackle Population Trend in Louisiana

All statesWetland birds

Boat-tailed Grackle in Louisiana has surged: up 132% on the route-weighted index since 1969.

+132%Since 1969TrendPercent 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 →
40Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Boat-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 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 →

Boat-tailed Grackle has surged in Louisiana: up 132% on the route-weighted index since 1969.

Boat-tailed Grackle Population Forecast in Louisiana

If the recent trend holds, Boat-tailed Grackle in Louisiana is projected to fall about 33% by 2030 — from 9.0 in 2025 to a central estimate of 6.0 (95% range 0.00–24). A 5-year backtest shows a typical error of ±529.4%, with 100% of held-out values landing inside the 95% band.

-33%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 →
6.0Projected 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 →
0.00–2495% 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 →
±529.4%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, Boat-tailed Grackle in Louisiana is projected to fall about 33% by 2030 — from 9.0 in 2025 to a central estimate of 6.0 (95% range 0.00–24). A 5-year backtest shows a typical error of ±529.4%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20267.00.0025
20276.80.0025
20286.50.0025
20296.30.0025
20306.00.0024

Boat-tailed Grackle Survey Routes in Louisiana

Routes recording Boat-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 →
Ltl Chenier22720251986
Ltl Chenier 222420112010
Gran Chenier21519821967
Forked Island 219120112010
Creole11919871967
Forked Island8220252008
Sabine Nwr4220081989
Sabine Nwr 24120172009
Berwick3920181990
Lafitte3219911967
Kaplan3120231999
Hackberry 23020252018
Gibson2620191999
Larose1419921988
De Ridder1119841984
Maurice820242023
Ville Platte819931992
Freetown719871978
Hackberry720041967
Woodlawn720212011
River Road620252015
Keystone619921992
Carlisle519881968
Junior519911987
Esther420251989

Boat-tailed Grackle Population Trend in Other States

alabamadelawarefloridageorgiamarylandmississippinew-jerseynew-yorknorth-carolinasouth-carolinatexasvirginia

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