BirdAnalyst
Species · Maine · BBS 2025 Release · 1966–2024

Ruby-crowned Kinglet Population Trend in Maine

All statesForest birds

Ruby-crowned Kinglet in Maine has collapsed: down 89% on the route-weighted index since 1968.

-89%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 →
63Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Ruby-crowned Kinglet Trends in MaineNotable 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 declinecomputed 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 →

Ruby-crowned Kinglet has collapsed in Maine: down 89% on the route-weighted index since 1968.

Ruby-crowned Kinglet Population Forecast in Maine

If the recent trend holds, Ruby-crowned Kinglet in Maine is projected to rise about 232% by 2029 — from 0.05 in 2024 to a central estimate of 0.18 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±130.2%, with 100% of held-out values landing inside the 95% band.

+232%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 →
0.18Projected 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 →
0.00–1.695% 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 →
±130.2%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, Ruby-crowned Kinglet in Maine is projected to rise about 232% by 2029 — from 0.05 in 2024 to a central estimate of 0.18 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±130.2%, with 100% 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 →
20250.280.001.7
20260.250.001.6
20270.230.001.6
20280.200.001.6
20290.180.001.6

Ruby-crowned Kinglet Survey Routes in Maine

Routes recording Ruby-crowned Kinglet in Maine.
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 →
Big Twenty1720081993
Pillsbury Pd1119681968
Big Twenty 2920092009
Yankeetuladi920091994
Moose River520081983
Weeks Brook520161995
Lake Moxie520102008
Northfield 2319981992
Otisfield Gr319751975
Bowdoin Ctr319751975
Harmony319961972
Benton319801977
Northfield319811976
Seboomook Lk320141978
St David320051982
Bethel219771977
Nesowadnehun220211991
Greenwood220052005
South Arm219991977
Hermon219921974
Hancock219871969
Aurora219981975
Grnd Lk Strm219991966
Waite219771977
Baker Lake 2220112011

Ruby-crowned Kinglet Population Trend in Other States

alaskaarizonacaliforniacoloradoidahomichiganminnesotamontananevadanew-hampshirenew-mexiconew-yorkoregonsouth-dakotautahvermontwashingtonwisconsinwyoming

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