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Species · BCR 34 · BBS 2026 Release · 1966–2025

Double-crested Cormorant In Sierra Madre Occidental

All regionsSierra Madre OccidentalWetland birds

Double-crested Cormorant in Sierra Madre Occidental has risen sharply: up 54% on the route-weighted index since 1993.

+54%Since 1993TrendPercent 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 →
5Routes 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 →
29YearsYears 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 risen sharply in Sierra Madre Occidental: up 54% on the route-weighted index since 1993.

Double-crested Cormorant In Sierra Madre Occidental Population Forecast

If the recent trend holds, Double-crested Cormorant in Sierra Madre Occidental is projected to rise about 22% by 2030 — from 0.37 in 2025 to a central estimate of 0.45 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±1426.8%, with 100% of held-out values landing inside the 95% band.

+22%Change by 2030TrendPercent 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 →
0.45Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.495% 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 →
±1426.8%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 Sierra Madre Occidental is projected to rise about 22% by 2030 — from 0.37 in 2025 to a central estimate of 0.45 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±1426.8%, with 100% of held-out values landing inside the 95% band.19872030
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 →
20260.450.001.4
20270.450.001.4
20280.450.001.4
20290.450.001.4
20300.450.001.4

Routes In Sierra Madre Occidental

Routes recording Double-crested Cormorant in Sierra Madre Occidental.
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 →
Peña BlancaARIZONA122001
AlpineARIZONA92025
PrescottARIZONA62017
WilliamsARIZONA12025
Carr MtnARIZONA12024

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.