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

Blue-gray Gnatcatcher Population Trend in New Jersey

All statesForest birds

Blue-gray Gnatcatcher in New Jersey has surged: up 23× on the route-weighted index since 1970.

23×Since 1970TrendPercent 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 →
36Routes 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 Blue-gray Gnatcatcher Trends in New JerseyNotable 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 →

Blue-gray Gnatcatcher has surged in New Jersey: up 23× on the route-weighted index since 1970.

Blue-gray Gnatcatcher Population Forecast in New Jersey

If the recent trend holds, Blue-gray Gnatcatcher in New Jersey is projected to fall about 23% by 2029 — from 4.1 in 2024 to a central estimate of 3.2 (95% range 2.2–4.2). A 5-year backtest shows a typical error of ±30.6%, with 60% of held-out values landing inside the 95% band.

-23%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 →
3.2Projected 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 →
2.2–4.295% 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 →
±30.6%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, Blue-gray Gnatcatcher in New Jersey is projected to fall about 23% by 2029 — from 4.1 in 2024 to a central estimate of 3.2 (95% range 2.2–4.2). A 5-year backtest shows a typical error of ±30.6%, with 60% 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 →
20253.02.04.0
20263.02.04.0
20273.12.14.1
20283.12.14.2
20293.22.24.2

Blue-gray Gnatcatcher Survey Routes in New Jersey

Routes recording Blue-gray Gnatcatcher in New Jersey.
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 →
Pomona2520241979
Bennett Mill2120001996
Winslow1720241989
Spraguetown 31520242021
Estell Manor1120222021
Hope819941975
Friendship820241982
Kemah Lake620241983
Holmansville520091991
Bennett Mill 2520242016
Albion420111966
Spraguetown419901981
Toms River320241994
Bloomsbury320231978
Gillette320241988
Pedricktown 2320192019
Six Points220221978
Spraguetown 2220122000
New Bedford220101971
Midvale220221979
High Point220241978
Dover220231977
Pottersville220221981
Roosevelt220181986
Cape May Ch220131992

Blue-gray Gnatcatcher Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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