BirdAnalyst
Species · BCR 28 · BBS 2025 Release · 1966–2024

Double-crested Cormorant In Appalachian Mountains

All regionsAppalachian MountainsWetland birds

Double-crested Cormorant in Appalachian Mountains has surged: up 14× on the route-weighted index since 1988.

14×Since 1988TrendPercent 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 →
63Routes 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 →
35YearsYears 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 Appalachian Mountains: up 14× on the route-weighted index since 1988.

Forecast

If the recent trend holds, Double-crested Cormorant in Appalachian Mountains is projected to stay roughly flat through 2029, near 0.11 (95% range 0.00–0.31). A 5-year backtest shows a typical error of ±106.9%, with 100% of held-out values landing inside the 95% band.

-8%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 →
0.11Projected 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 →
0.00–0.3195% 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 →
±106.9%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 Appalachian Mountains is projected to stay roughly flat through 2029, near 0.11 (95% range 0.00–0.31). A 5-year backtest shows a typical error of ±106.9%, with 100% of held-out values landing inside the 95% band.19732029
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 →
20250.100.000.30
20260.110.000.31
20270.110.000.31
20280.110.000.31
20290.110.000.31

Routes In Appalachian Mountains

Routes recording Double-crested Cormorant in Appalachian Mountains.
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 →
GuntersvilleALABAMA152024
CanadensisPENNSYLVANIA132015
ArnotPENNSYLVANIA102012
RosecransPENNSYLVANIA82003
BrunnervillePENNSYLVANIA82009
RushPENNSYLVANIA72024
SunnybrookKENTUCKY52011
Davis CrossroadsGEORGIA42021
Pine GroveALABAMA32024
OldtownMARYLAND32021
WolfsvilleMARYLAND32005
FinzelMARYLAND32014
BloomsburyNEW-JERSEY32018
High PointNEW-JERSEY32003
DoverNEW-JERSEY32022
MiddletownPENNSYLVANIA32014
GreensportALABAMA22019
GreentownPENNSYLVANIA22014
Brunnerville 2PENNSYLVANIA22017
Signal MtnTENNESSEE22024
ClintonWEST-VIRGINIA22017
OdenvilleALABAMA12021
KymulgaALABAMA12022
StevensonALABAMA12012
RiversideALABAMA12013

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