BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Green Heron

ArdeidaeWetland birdsButorides virescens

Green Heron has fallen sharply: down 67% on the route-weighted index since 1968.

-67%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 →
2,421RoutesSurvey 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 Green Heron

The Green Heron (Butorides virescens) is a North American member of the Herons, Egrets & Bitterns (Ardeidae). In this analysis it is grouped with the wetland birds.

Size
12–51 in long (30–130 cm) — a long-legged wader (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 2,421 Breeding Bird Survey routes across 43 states, most concentrated in the Appalachian Mountains.
Family
Ardeidae · Wetland birds

Notable Green 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 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 →

Green Heron has fallen sharply in surveyed states: down 66% on the route-weighted index since 1968.

Green Heron Population Forecast

If the recent trend holds, Green Heron is projected to fall about 43% by 2029 — from 0.28 in 2024 to a central estimate of 0.16 (95% range 0.04–0.28). A 5-year backtest shows a typical error of ±16.6%, with 100% of held-out values landing inside the 95% band.

-43%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 →
0.16Projected 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 →
0.04–0.2895% 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 →
±16.6%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, Green Heron is projected to fall about 43% by 2029 — from 0.28 in 2024 to a central estimate of 0.16 (95% range 0.04–0.28). A 5-year backtest shows a typical error of ±16.6%, with 100% 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 →
20250.200.080.33
20260.190.070.31
20270.180.060.30
20280.170.050.29
20290.160.040.28

Where the Green Heron Is Detected

BBS routes recording Green Heron, sized by most recent count.

Green Heron Population Trend by State

Green 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-54%1968106
Arizona-72%198211
Arkansas-67%196950
California-10%197293
Connecticut-46%196917
Delaware+70%196817
Florida-64%1968117
Georgia-63%196896
Illinois-27%1968101
Indiana-66%196861
Iowa-14%197032
Kansas-77%196947
Kentucky-74%196860
Louisiana-39%196998
Maine-77%196822
Maryland-45%196874
Massachusetts-22%196928
Michigan+52%196877
Minnesota-14%196962
Mississippi+4%196861
Missouri-50%196984
Nebraska-68%197219
Nevadainsufficient datan/a1
New Hampshire-37%196818
New Jersey-57%196839
New Mexico-25%19935
New York-35%1968106
North Carolina-50%196895
North Dakotainsufficient datan/a1
Ohio-57%196878
Oklahoma-79%196963
Oregon-86%197126
Pennsylvania-54%1968123
Rhode Island-55%19726
South Carolina-56%196846
South Dakota+42%19749
Tennessee-75%196849
Texas-52%1969170
Vermont-72%197020
Virginia-62%196866
Washington-73%197821
West Virginia-85%196854
Wisconsin+18%196892

Green Heron Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Green 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-79%197160
Great Basin+87%19718
Prairie Potholes-38%197136
Boreal Hardwood Transition-4%196878
Lower Great Lakes / St. Lawrence Plain-12%196881
Atlantic Northern Forest-66%196867
Shortgrass Prairie-88%19789
Central Mixed Grass Prairie-9%196981
Edwards Plateau-6%197116
Oaks and Prairies-49%196973
Eastern Tallgrass Prairie-55%1968242
Prairie Hardwood Transition+38%1968154
Central Hardwoods-78%1968151
West Gulf Coastal Plain / Ouachitas-83%1969100
Mississippi Alluvial Valley+19%196970
Southeastern Coastal Plain-52%1968317
Appalachian Mountains-65%1968335
Piedmont-50%1968150
New England / Mid-Atlantic Coast-47%1968154
Peninsular Florida-68%196879
Coastal California+38%197263
Sonoran and Mojave Deserts-16%197913
Chihuahuan Desert-60%19956
Tamaulipan Brushlands-3%197023
Gulf Coastal Prairie-23%196946

Green Heron Conservation Status

Our route-weighted index shows it down 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.