BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Common Loon

GaviidaeWetland birdsGavia immer

Common Loon has increased: up 44% on the route-weighted index since 1968.

+44%Since 1968TrendPercent 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 →
414RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Common Loon

The Common Loon (Gavia immer) is a North American member of the Loons (Gaviidae). In this analysis it is grouped with the wetland birds.

Size
23.5–35.5 in long (60–90 cm) — a large diving bird (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 414 Breeding Bird Survey routes across 15 states, most concentrated in the Boreal Hardwood Transition.
Family
Gaviidae · Wetland birds

Notable Common Loon TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Common Loon. See the full index history below.

Common Loon Population Forecast

If the recent trend holds, Common Loon is projected to stay roughly flat through 2029, near 0.10 (95% range 0.08–0.13). A 5-year backtest shows a typical error of ±41.3%, with 40% of held-out values landing inside the 95% band.

+9%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 →
0.10Projected 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 →
0.08–0.1395% 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 →
±41.3%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 is projected to stay roughly flat through 2029, near 0.10 (95% range 0.08–0.13). A 5-year backtest shows a typical error of ±41.3%, with 40% of held-out values landing inside the 95% band.19662029
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 →
20250.100.070.13
20260.100.070.13
20270.100.070.13
20280.100.070.13
20290.100.080.13

Where the Common Loon Is Detected

BBS routes recording Common Loon, sized by most recent count.

Common Loon Population Trend by State

Common Loon population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alaska-45%197878
Idahoinsufficient datan/a6
Maine+111%196865
Massachusettsinsufficient datan/a3
Michigan+117%196860
Minnesota-10%196950
Montana-9%197915
New Hampshire+283%196920
New York+65%196825
North Dakotainsufficient datan/a1
Oregoninsufficient datan/a1
Vermont+316%197810
Washington-11%197727
Wisconsin+20%196847
Wyoming-47%19916

Common Loon Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Common Loon population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
BCR 2+89%198814
BCR 4-49%198341
Northern Pacific Rainforest+103%197631
Great Basin-78%198514
Northern Rockies-23%197928
Prairie Potholes+40%19789
Boreal Hardwood Transition-1%1968112
Lower Great Lakes / St. Lawrence Plain+38%19837
Atlantic Northern Forest+211%1968107
Prairie Hardwood Transition+74%196838
New England / Mid-Atlantic Coast+188%19738

Common Loon Conservation Status

Our route-weighted index shows it up about 44% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.