BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Great Blue Heron

ArdeidaeWetland birdsArdea herodias

Great Blue Heron has risen sharply: up 66% on the route-weighted index since 1968.

+66%Since 1968TrendPercent 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 →
3,397RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Great Blue Heron

The largest and most widespread North American heron, the Great Blue Heron stalks shallows and fields, standing motionless before spearing prey.

Size
38–54 in long, about 5.3 lb (97–137 cm, 2.4 kg)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Fish, plus amphibians, reptiles, small mammals and birds.
Range
Recorded on 3,397 Breeding Bird Survey routes across 49 states, most concentrated in the Appalachian Mountains.
Family
Ardeidae · Wetland birds
Conservation
Least Concern

Notable Great Blue Heron TrendsNotable 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 risen sharply in surveyed states: up 66% on the route-weighted index since 1968.

Great Blue Heron Population Forecast

If the recent trend holds, Great Blue Heron is projected to rise about 53% by 2029 — from 0.71 in 2024 to a central estimate of 1.1 (95% range 0.66–1.5). A 5-year backtest shows a typical error of ±58%, with 20% 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 →
1.1Projected 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 →
0.66–1.595% 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 →
±58%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 is projected to rise about 53% by 2029 — from 0.71 in 2024 to a central estimate of 1.1 (95% range 0.66–1.5). A 5-year backtest shows a typical error of ±58%, with 20% of held-out values landing inside the 95% band.19662029
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 →
20251.10.641.5
20261.10.641.5
20271.10.651.5
20281.10.651.5
20291.10.661.5

Where the Great Blue Heron Is Detected

BBS routes recording Great Blue Heron, sized by most recent count.

Great Blue Heron Population Trend by State

Great Blue Heron population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alabama+259%1968106
Alaska-97%197321
Arizona+241%197540
Arkansas+423%196955
California+19%1970156
Colorado+219%197398
Connecticut+768%197518
Delaware34×196817
Florida-51%1968122
Georgia+8%1968105
Idaho+157%197241
Illinois+257%1968105
Indiana+229%196869
Iowa+515%197038
Kansas+80%196960
Kentucky16×196853
Louisiana+101%196994
Maine-33%196862
Maryland+99%196873
Massachusetts13×196928
Michigan+160%196895
Minnesota-49%196989
Mississippi15×196968
Missouri+188%197090
Montana-57%197085
Nebraska+398%197067
Nevada-25%197221
New Hampshire+83%196824
New Jersey+401%196835
New Mexico+71%199231
New York+114%1968123
North Carolina+406%196896
North Dakota+224%196945
Ohio+41%196886
Oklahoma+88%196967
Oregon-12%197186
Pennsylvania+343%1968124
Rhode Island+22%19927
South Carolina+57%196845
South Dakota+2%196951
Tennessee30×197048
Texas+29%1969198
Utah-40%197040
Vermont+15%196925
Virginia+160%196871
Washington-46%197083
West Virginia+390%198351
Wisconsin-10%196897
Wyoming+39%197488

Great Blue Heron Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Great Blue Heron population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Pacific Rainforest-47%1970118
Great Basin+9%1970148
Northern Rockies-24%1970144
Prairie Potholes+214%1969105
Boreal Hardwood Transition-60%1968110
Lower Great Lakes / St. Lawrence Plain+86%196885
Atlantic Northern Forest+42%1968135
Sierra Nevada-15%197618
Southern Rockies / Colorado Plateau+480%1972107
Badlands and Prairies-29%196998
Shortgrass Prairie+12%197081
Central Mixed Grass Prairie+191%1969121
Edwards Plateau-40%197018
Oaks and Prairies+53%196974
Eastern Tallgrass Prairie+223%1968275
Prairie Hardwood Transition+3%1968161
Central Hardwoods20×1968158
West Gulf Coastal Plain / Ouachitas+38%196999
Mississippi Alluvial Valley+639%196969
Southeastern Coastal Plain+43%1968327
Appalachian Mountains+437%1968340
Piedmont20×1970153
New England / Mid-Atlantic Coast+220%1968149
Peninsular Florida-46%196880
Coastal California+70%197083
Sonoran and Mojave Deserts+121%197329
Sierra Madre Occidental+23%197823
Chihuahuan Desert+56%197520
Tamaulipan Brushlands-19%197221
Gulf Coastal Prairie+59%196948

Great Blue Heron Conservation Status

Least Concern

The IUCN Red List rates this species as Least Concern. Our route-weighted index shows it up about 66% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.