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

Common Grackle Population Trend in Louisiana

All statesGeneralists

Common Grackle in Louisiana has collapsed: down 84% on the route-weighted index since 1969.

-84%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 →
100Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common 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 →

Common Grackle has collapsed in Louisiana: down 84% on the route-weighted index since 1969.

Common Grackle Population Forecast in Louisiana

If the recent trend holds, Common Grackle in Louisiana is projected to fall about 53% by 2029 — from 10 in 2024 to a central estimate of 4.8 (95% range 0.00–32). A 5-year backtest shows a typical error of ±16%, 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 →
4.8Projected 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 →
0.00–3295% 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 →
±16%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, Common Grackle in Louisiana is projected to fall about 53% by 2029 — from 10 in 2024 to a central estimate of 4.8 (95% range 0.00–32). A 5-year backtest shows a typical error of ±16%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20258.90.0036
20267.90.0035
20276.90.0034
20285.80.0033
20294.80.0032

Common Grackle Survey Routes in Louisiana

Routes recording Common 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 →
Morgan City26019861967
Junior24819911987
Woodlawn23820212008
Carlisle13619881968
Lafitte13519911967
Gibson11420191999
Berwick10320181987
Morgan City10220222011
Larose7419921988
River Road6520241987
Esther6220241988
Natchitoches4319911987
Gonzales4220191998
Easton4119901967
Oakdale3919941991
Creole3819871971
Ramah3620241988
Fillmore3419891968
Keystone3320131967
Shaw3320241967
Freetown3220191967
Vinton3120092008
Kraemer2820241997
Forked Island 22820112010
Port Allen2720242000

Common Grackle Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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