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

Purple Martin Population Trend in New Jersey

All statesAerial insectivores

Purple Martin in New Jersey has fallen sharply: down 58% on the route-weighted index since 1968.

-58%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 →
39Routes 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 Purple Martin 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 →

Purple Martin has fallen sharply in New Jersey: down 58% on the route-weighted index since 1968.

Purple Martin Population Forecast in New Jersey

If the recent trend holds, Purple Martin in New Jersey is projected to fall about 45% by 2029 — from 5.6 in 2024 to a central estimate of 3.1 (95% range 0.00–6.9). A 5-year backtest shows a typical error of ±37.3%, with 100% of held-out values landing inside the 95% band.

-45%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 →
3.1Projected 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 →
0.00–6.995% 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 →
±37.3%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, Purple Martin in New Jersey is projected to fall about 45% by 2029 — from 5.6 in 2024 to a central estimate of 3.1 (95% range 0.00–6.9). A 5-year backtest shows a typical error of ±37.3%, 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 →
20253.30.007.1
20263.20.007.1
20273.20.007.0
20283.10.007.0
20293.10.006.9

Purple Martin Survey Routes in New Jersey

Routes recording Purple Martin 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 →
Pedricktown 24820242013
Woodbury Hgt3620241967
Cape May Ch3220131992
Holmansville2419961969
Six Points2020241978
Pedricktown1520121991
Albion920221966
Ancora619771966
Mt Misery619881976
Bennett Mill 2620242016
Deepwater519771969
Villas519811979
Del Haven519911991
Bennett Mill420001966
Robbinsville419781966
Spraguetown419841977
Sandbrook319961972
Hope319901974
Greenwich220231966
Toms River219951966
New Bedford220241970
Kemah Lake220241968
Dover220231977
Gillette220242012
Cranbury220101987

Purple Martin Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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