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

Northern Parula Population Trend in Connecticut

All statesForest birds

Northern Parula in Connecticut has surged: up 101% on the route-weighted index since 1973.

+101%Since 1973TrendPercent 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 StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
28YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Northern Parula Trends in ConnecticutNotable 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 →

Northern Parula has surged in Connecticut: up 101% on the route-weighted index since 1973.

Northern Parula Population Forecast in Connecticut

If the recent trend holds, Northern Parula in Connecticut is projected to rise about 87% by 2024 — from 0.15 in 2019 to a central estimate of 0.29 (95% range 0.08–0.49). A 5-year backtest shows a typical error of ±77.7%, with 60% of held-out values landing inside the 95% band.

+87%Change by 2024TrendPercent 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 →
0.29Projected 2024 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.08–0.4995% 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 →
±77.7%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, Northern Parula in Connecticut is projected to rise about 87% by 2024 — from 0.15 in 2019 to a central estimate of 0.29 (95% range 0.08–0.49). A 5-year backtest shows a typical error of ±77.7%, with 60% of held-out values landing inside the 95% band.19712024
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 →
20200.270.060.48
20210.280.070.48
20220.280.070.49
20230.280.080.49
20240.290.080.49

Northern Parula Survey Routes in Connecticut

Routes recording Northern Parula in Connecticut.
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 →
Willimantic220002000
Warren 2220192012
E Hartland119911987
Buckingham120031971
Uncasville120132011
No Woodbury120182003
Sherman120181973
Greenwich119721972
Warren120032003
Mid Haddam119961974

Northern Parula Population Trend in Other States

alabamaarkansascaliforniadelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsin

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