BirdAnalyst
Species · BCR 29 · BBS 2025 Release · 1966–2024

Great Blue Heron In Piedmont

All regionsPiedmontWetland birds

Great Blue Heron in Piedmont has surged: up 20× on the route-weighted index since 1970.

20×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 →
153Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 Piedmont: up 20× on the route-weighted index since 1970.

Great Blue Heron In Piedmont Population Forecast

If the recent trend holds, Great Blue Heron in Piedmont is projected to rise about 62% by 2029 — from 0.76 in 2024 to a central estimate of 1.2 (95% range 0.74–1.7). A 5-year backtest shows a typical error of ±68.3%, with 40% of held-out values landing inside the 95% band.

+62%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 →
1.2Projected 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 →
0.74–1.795% 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 →
±68.3%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 Piedmont is projected to rise about 62% by 2029 — from 0.76 in 2024 to a central estimate of 1.2 (95% range 0.74–1.7). A 5-year backtest shows a typical error of ±68.3%, with 40% 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 →
20251.10.661.6
20261.20.681.7
20271.20.701.7
20281.20.721.7
20291.20.741.7

Routes In Piedmont

Routes recording Great Blue Heron in Piedmont.
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 →
HallVIRGINIA92023
Bald FriarMARYLAND51996
LincolntonGEORGIA42013
RutledgeGEORGIA42024
Rock BranchGEORGIA42024
EmmitsburgMARYLAND42024
Upper XrdsMARYLAND42007
CrotonNEW-JERSEY42002
Mount AiryNORTH-CAROLINA42024
AkronPENNSYLVANIA41997
Mt Gretna 2PENNSYLVANIA42018
ShrewsburyPENNSYLVANIA42019
BrodnaxVIRGINIA42023
Sunny SideGEORGIA32017
HebronGEORGIA32019
IjamsvilleMARYLAND32024
PottersvilleNEW-JERSEY32023
ArcolaNORTH-CAROLINA32024
WilgroveNORTH-CAROLINA32023
FlayNORTH-CAROLINA32023
BullockNORTH-CAROLINA32024
BendersvillePENNSYLVANIA32024
DavidVIRGINIA32013
GrovetownGEORGIA22019
MetasvilleGEORGIA22000

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