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

Great Blue Heron Population Trend in Tennessee

All statesWetland birds

Great Blue Heron in Tennessee has surged: up 30× on the route-weighted index since 1970.

30×Since 1970TrendPercent 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 →
48Routes 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 →
54YearsYears 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 Blue Heron Trends in TennesseeNotable 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 →

Great Blue Heron has surged in Tennessee: up 30× on the route-weighted index since 1970.

Great Blue Heron Population Forecast in Tennessee

If the recent trend holds, Great Blue Heron in Tennessee is projected to rise about 32% by 2029 — from 1.5 in 2024 to a central estimate of 2.0 (95% range 0.72–3.4). A 5-year backtest shows a typical error of ±78.1%, with 100% of held-out values landing inside the 95% band.

+32%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 →
2.0Projected 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 →
0.72–3.495% 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 →
±78.1%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 Blue Heron in Tennessee is projected to rise about 32% by 2029 — from 1.5 in 2024 to a central estimate of 2.0 (95% range 0.72–3.4). A 5-year backtest shows a typical error of ±78.1%, 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 →
20252.00.643.3
20262.00.663.3
20272.00.683.3
20282.00.703.3
20292.00.723.4

Great Blue Heron Survey Routes in Tennessee

Routes recording Great Blue Heron in Tennessee.
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 →
Peytonsville820231997
Signal Mtn720241984
Pawpaw720121969
Mansfield620241969
Humboldt420241977
Tiptonville320231971
Collinwood320241993
Campbellsville320171991
Jasper320241991
Oliver Spgs320211986
Jefferson Cty320111967
Allens Brdge320221990
Big Sandy220241981
Sweetlips220191989
Pond Creek220221997
Lewis Forest220241983
Petersburg220131997
Tullahoma220151983
Glen220241984
Climer220021982
Corryton Rd219951989
Pawpaw 2220232013
Indian Mound 2220232004
Moscow120221995
Brownsville120101988

Great Blue Heron Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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