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Species · BCR 4 · BBS 2025 Release · 1966–2024

Tundra Swan In BCR 4

All regionsBCR 4Waterfowl

Tundra Swan in BCR 4 has risen sharply: up 63% on the route-weighted index since 1994.

+63%Since 1994TrendPercent 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 →
10Routes 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 →

Tundra Swan has risen sharply in BCR 4: up 63% on the route-weighted index since 1994.

Tundra Swan In BCR 4 Population Forecast

If the recent trend holds, Tundra Swan in BCR 4 is projected to rise about 15% by 2029 — from 0.11 in 2024 to a central estimate of 0.13 (95% range 0.00–0.29). A 5-year backtest shows a typical error of ±135.4%, with 80% of held-out values landing inside the 95% band.

+15%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 →
0.13Projected 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 →
0.00–0.2995% 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 →
±135.4%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, Tundra Swan in BCR 4 is projected to rise about 15% by 2029 — from 0.11 in 2024 to a central estimate of 0.13 (95% range 0.00–0.29). A 5-year backtest shows a typical error of ±135.4%, with 80% of held-out values landing inside the 95% band.19912029
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 →
20250.130.000.28
20260.130.000.28
20270.130.000.28
20280.130.000.28
20290.130.000.29

Routes In BCR 4

Routes recording Tundra Swan in BCR 4.
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 →
Unalakleet RiverALASKA32019
Mud RiverALASKA32024
MaclarenALASKA22021
MonahanALASKA22004
Hather CreekALASKA22012
Anvik RiverALASKA22014
Birch LakeALASKA12019
SlanaALASKA12018
Nicholai SlALASKA12006
ColdfootALASKA12024

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