BirdAnalyst
Species · BCR 15 · BBS 2025 Release · 1966–2024

Mallard In Sierra Nevada

All regionsSierra NevadaWaterfowl

Mallard in Sierra Nevada has surged: up 101% on the route-weighted index since 1973.

+101%Since 1973TrendPercent 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 →
27Routes 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 →
50YearsYears 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 →

Mallard has surged in Sierra Nevada: up 101% on the route-weighted index since 1973.

Mallard In Sierra Nevada Population Forecast

If the recent trend holds, Mallard in Sierra Nevada is projected to rise about 78% by 2029 — from 0.84 in 2024 to a central estimate of 1.5 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±159.1%, with 100% of held-out values landing inside the 95% band.

+78%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 →
0.00–3.495% 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 →
±159.1%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, Mallard in Sierra Nevada is projected to rise about 78% by 2029 — from 0.84 in 2024 to a central estimate of 1.5 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±159.1%, with 100% of held-out values landing inside the 95% band.19712029
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 →
20251.40.003.3
20261.40.003.3
20271.50.003.3
20281.50.003.4
20291.50.003.4

Routes In Sierra Nevada

Routes recording Mallard in Sierra Nevada.
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 →
Last ChanceCALIFORNIA82019
PaxtonCALIFORNIA72024
Lassen ParkCALIFORNIA61989
LakeshoreCALIFORNIA32024
Tuolumne GroveCALIFORNIA22024
Hat CreekCALIFORNIA22016
Pollock PinesCALIFORNIA22012
Eagle LakeCALIFORNIA12017
DardanelleCALIFORNIA11988
Bass LakeCALIFORNIA12017
WoodfordsCALIFORNIA12003
SattleyCALIFORNIA12019
Butte MeadowCALIFORNIA11998
GeneseeCALIFORNIA12024
Higgins CornCALIFORNIA12013
DownievilleCALIFORNIA11994
RivertonCALIFORNIA12001
Chaos CraterCALIFORNIA12018
GoumazCALIFORNIA12011
Meadow ValleyCALIFORNIA12024
Little TruckeeCALIFORNIA12021
PlacervilleCALIFORNIA12024
CoultervilleCALIFORNIA12007
WawonaCALIFORNIA12002
Pine MountainCALIFORNIA12016

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