BirdAnalyst
Species · BCR 5 · BBS 2025 Release · 1966–2024

Caspian Tern In Northern Pacific Rainforest

All regionsNorthern Pacific RainforestWetland birds

Caspian Tern in Northern Pacific Rainforest has surged: up 117% on the route-weighted index since 1975.

+117%Since 1975TrendPercent 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 →
23Routes 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 →

Caspian Tern has surged in Northern Pacific Rainforest: up 117% on the route-weighted index since 1975.

Caspian Tern In Northern Pacific Rainforest Population Forecast

If the recent trend holds, Caspian Tern in Northern Pacific Rainforest is projected to rise about 636% by 2029 — from 0.05 in 2024 to a central estimate of 0.39 (95% range 0.03–0.75). A 5-year backtest shows a typical error of ±215.2%, with 80% of held-out values landing inside the 95% band.

+636%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 →
0.39Projected 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 →
0.03–0.7595% 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 →
±215.2%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, Caspian Tern in Northern Pacific Rainforest is projected to rise about 636% by 2029 — from 0.05 in 2024 to a central estimate of 0.39 (95% range 0.03–0.75). A 5-year backtest shows a typical error of ±215.2%, with 80% of held-out values landing inside the 95% band.19682029
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 →
20250.370.010.74
20260.380.010.74
20270.380.020.74
20280.390.020.75
20290.390.030.75

Routes In Northern Pacific Rainforest

Routes recording Caspian Tern in Northern Pacific Rainforest.
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 →
HoneydewCALIFORNIA42011
GlasgowOREGON42021
Port AngelesWASHINGTON42023
McchordWASHINGTON41998
WedderburnOREGON32004
Bunker HillWASHINGTON32000
MukilteoWASHINGTON32023
Warm Beach 2WASHINGTON32024
YakutatALASKA22023
Fish RockCALIFORNIA22013
SvensenOREGON21990
Warm BeachWASHINGTON22017
South ElmaWASHINGTON21990
DeceptionWASHINGTON21997
MccloudCALIFORNIA11980
Bodega BayCALIFORNIA12019
YrekaCALIFORNIA12006
Hazel CampOREGON12013
Nicolai Mtn.OREGON12014
TaholahWASHINGTON12017
IlwacoWASHINGTON12024
RaymondWASHINGTON12018
Vashon Is.WASHINGTON12023

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