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

Field Sparrow Population Trend in New Jersey

All statesGeneralists

Field Sparrow in New Jersey has fallen sharply: down 69% on the route-weighted index since 1968.

-69%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 →
41Routes 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 Field Sparrow 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 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 →

Field Sparrow has fallen sharply in New Jersey: down 69% on the route-weighted index since 1968.

Field Sparrow Population Forecast in New Jersey

If the recent trend holds, Field Sparrow in New Jersey is projected to fall about 56% by 2029 — from 3.2 in 2024 to a central estimate of 1.4 (95% range 0.00–4.5). A 5-year backtest shows a typical error of ±49.5%, with 100% of held-out values landing inside the 95% band.

-56%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 →
1.4Projected 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 →
0.00–4.595% 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 →
±49.5%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, Field Sparrow in New Jersey is projected to fall about 56% by 2029 — from 3.2 in 2024 to a central estimate of 1.4 (95% range 0.00–4.5). A 5-year backtest shows a typical error of ±49.5%, 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 →
20251.80.004.8
20261.70.004.8
20271.60.004.7
20281.50.004.6
20291.40.004.5

Field Sparrow Survey Routes in New Jersey

Routes recording Field Sparrow 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 →
Croton1720071970
Hope1119941970
Pedricktown 21020242013
Pedricktown1020121991
Holmansville920091969
Villas919811979
Deepwater819771969
Ramseysburg820241995
High Point720241977
Cranbury720231993
Woodbury Hgt620241967
Sandbrook620241969
Croton 2620242008
Greenwich420241966
Spraguetown 2420072000
Mt Misery419881976
Winslow420241989
Toms River320241966
Ancora319771966
Masonville319701966
Kemah Lake320241966
Bloomsbury320241969
Cape May Ch320131992
Clarksville219911969
Robbinsville219791966

Field Sparrow Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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