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

Blue Grosbeak Population Trend in Louisiana

All statesGeneralists

Blue Grosbeak in Louisiana has surged: up 290% on the route-weighted index since 1969.

+290%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 →
84Routes 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 Blue Grosbeak 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 →

Blue Grosbeak has surged in Louisiana: up 290% on the route-weighted index since 1969.

Blue Grosbeak Population Forecast in Louisiana

If the recent trend holds, Blue Grosbeak in Louisiana is projected to fall about 18% by 2029 — from 3.8 in 2024 to a central estimate of 3.2 (95% range 1.5–4.8). A 5-year backtest shows a typical error of ±15%, with 100% of held-out values landing inside the 95% band.

-18%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 →
3.2Projected 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 →
1.5–4.895% 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 →
±15%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, Blue Grosbeak in Louisiana is projected to fall about 18% by 2029 — from 3.8 in 2024 to a central estimate of 3.2 (95% range 1.5–4.8). A 5-year backtest shows a typical error of ±15%, 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 →
20253.01.44.7
20263.11.44.7
20273.11.44.8
20283.11.54.8
20293.21.54.8

Blue Grosbeak Survey Routes in Louisiana

Routes recording Blue Grosbeak 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 →
Fillmore1319891968
Many1219921989
Norwood1220242006
Flat Creek1220241998
Ivan1220131998
Franklinton1120242008
Ivan 21020162014
Goodwill1020242004
Easton919901976
Clay920241970
Trout920241994
Evelyn920242004
Shaw820231967
Longstreet820241967
Frogmore820241998
Linville820241998
Hargis820102006
Enterprise820242006
Derry719891970
Mount Union720241998
Concord720192006
Turkey Creek719981998
Fort Jessup620231998
Roseland520241967
Bickham520241984

Blue Grosbeak Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradodelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckymarylandminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvirginiawest-virginiawyoming

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