BirdAnalyst
Species · BCR 30 · BBS 2025 Release · 1966–2024

Double-crested Cormorant In New England / Mid-Atlantic Coast

All regionsNew England / Mid-Atlantic CoastWetland birds

Double-crested Cormorant in New England / Mid-Atlantic Coast has surged: up 25× on the route-weighted index since 1970.

25×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 →
111Routes 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 →

Double-crested Cormorant has surged in New England / Mid-Atlantic Coast: up 25× on the route-weighted index since 1970.

Double-crested Cormorant In New England / Mid-Atlantic Coast Population Forecast

If the recent trend holds, Double-crested Cormorant in New England / Mid-Atlantic Coast is projected to rise about 580% by 2029 — from 0.22 in 2024 to a central estimate of 1.5 (95% range 0.52–2.5). A 5-year backtest shows a typical error of ±127.7%, with 80% of held-out values landing inside the 95% band.

+580%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 →
1.5Projected 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 →
0.52–2.595% 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 →
±127.7%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, Double-crested Cormorant in New England / Mid-Atlantic Coast is projected to rise about 580% by 2029 — from 0.22 in 2024 to a central estimate of 1.5 (95% range 0.52–2.5). A 5-year backtest shows a typical error of ±127.7%, with 80% 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 →
20251.40.452.5
20261.50.462.5
20271.50.482.5
20281.50.502.5
20291.50.522.5

Routes In New England / Mid-Atlantic Coast

Routes recording Double-crested Cormorant in New England / Mid-Atlantic Coast.
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 →
MadisonMARYLAND562023
ShannockRHODE-ISLAND542023
PomfretMARYLAND301998
St. George'S IslandMARYLAND252017
Port RoyalVIRGINIA242019
ChilmarkMASSACHUSETTS221983
HughesvilleMARYLAND202009
NortheastMARYLAND202008
SharpsVIRGINIA132013
Cape CharlesVIRGINIA122018
NewburyportMASSACHUSETTS112022
PedricktownNEW-JERSEY102006
Chincoteag WVIRGINIA102022
LittletonMASSACHUSETTS92000
Ocean CityNEW-JERSEY82024
DanburyCONNECTICUT72013
FredericaDELAWARE62007
Block IslandRHODE-ISLAND62010
Cape Cod NsMASSACHUSETTS51996
WesthamptonNEW-YORK52006
Quonset PtRHODE-ISLAND52022
Mid HaddamCONNECTICUT42022
Bethany BchDELAWARE41990
BrocktonMASSACHUSETTS42018
Bennett MillNEW-JERSEY41998

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