BirdAnalyst
Species · New Hampshire · BBS 2025 Release · 1966–2024

Common Loon Population Trend in New Hampshire

All statesWetland birds

Common Loon in New Hampshire has surged: up 283% on the route-weighted index since 1969.

+283%Since 1969TrendPercent 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 →
20Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common Loon Trends in New HampshireNotable 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 →

Common Loon has surged in New Hampshire: up 283% on the route-weighted index since 1969.

Common Loon Population Forecast in New Hampshire

If the recent trend holds, Common Loon in New Hampshire is projected to rise about 15% by 2029 — from 0.41 in 2024 to a central estimate of 0.47 (95% range 0.24–0.70). A 5-year backtest shows a typical error of ±56.9%, 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 →
0.47Projected 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 →
0.24–0.7095% 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 →
±56.9%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, Common Loon in New Hampshire is projected to rise about 15% by 2029 — from 0.41 in 2024 to a central estimate of 0.47 (95% range 0.24–0.70). A 5-year backtest shows a typical error of ±56.9%, with 80% of held-out values landing inside the 95% band.19672029
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 →
20250.450.210.68
20260.450.220.68
20270.460.230.69
20280.470.230.70
20290.470.240.70

Common Loon Survey Routes in New Hampshire

Routes recording Common Loon in New Hampshire.
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 →
Strafford320241969
Marlow220212021
Jefferson Hl220221994
Glen220241981
Brentwood119811981
Fitzwilliam120242021
Dover120132003
Hopkinton120121998
Epsom120191970
Canterbury120212012
Gilmantn I W120181991
Mt Chocorua120231973
Walpole120241976
Lempster120162016
Crawford Not119681968
Franconia120042004
Milan120241986
Stratford120011969
Dixvil Notch120102010
Clarksville120241967

Common Loon Population Trend in Other States

alaskaidahomainemassachusettsmichiganminnesotamontananew-yorknorth-dakotaoregonvermontwashingtonwisconsinwyoming

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