BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Neotropic Cormorant

PhalacrocoracidaeWetland birdsNannopterum brasilianum

Neotropic Cormorant has surged: up 155% on the route-weighted index since 1971.

+155%Since 1971TrendPercent 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 →
75RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
51Years 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 Neotropic Cormorant

The Neotropic Cormorant (Nannopterum brasilianum) is a North American member of the Cormorants (Phalacrocoracidae). In this analysis it is grouped with the wetland birds.

Size
27.5–35.5 in long (70–90 cm) — a large diving waterbird (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 75 Breeding Bird Survey routes across 4 states, most concentrated in the Gulf Coastal Prairie.
Family
Phalacrocoracidae · Wetland birds

Notable Neotropic Cormorant TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Neotropic Cormorant. See the full index history below.

Neotropic Cormorant Population Forecast

If the recent trend holds, Neotropic Cormorant is projected to rise about 77% by 2029 — from 0.06 in 2024 to a central estimate of 0.11 (95% range 0.00–0.23). A 5-year backtest shows a typical error of ±93.3%, with 100% of held-out values landing inside the 95% band.

+77%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 →
0.00–0.2395% 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 →
±93.3%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, Neotropic Cormorant is projected to rise about 77% by 2029 — from 0.06 in 2024 to a central estimate of 0.11 (95% range 0.00–0.23). A 5-year backtest shows a typical error of ±93.3%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.100.000.22
20260.100.000.23
20270.110.000.23
20280.110.000.23
20290.110.000.23

Where the Neotropic Cormorant Is Detected

BBS routes recording Neotropic Cormorant, sized by most recent count.

Neotropic Cormorant Population Trend by State

Neotropic Cormorant 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 →
Arizonainsufficient datan/a2
Louisiana-75%197324
New Mexicoinsufficient datan/a3
Texas+419%197646

Neotropic Cormorant Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Neotropic Cormorant 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 →
Oaks and Prairies+345%20056
Mississippi Alluvial Valley+231%20047
Tamaulipan Brushlands-50%197814
Gulf Coastal Prairie+142%197135

Neotropic Cormorant Conservation Status

Our route-weighted index shows it up about 155% since 1971.

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