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

Chimney Swift Population Trend in Wisconsin

All statesAerial insectivores

Chimney Swift in Wisconsin has fallen sharply: down 55% on the route-weighted index since 1968.

-55%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 →
96Routes 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 Chimney Swift Trends in WisconsinNotable 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 →

Chimney Swift has fallen sharply in Wisconsin: down 55% on the route-weighted index since 1968.

Chimney Swift Population Forecast in Wisconsin

If the recent trend holds, Chimney Swift in Wisconsin is projected to rise about 33% by 2029 — from 1.9 in 2024 to a central estimate of 2.6 (95% range 0.61–4.5). A 5-year backtest shows a typical error of ±56.2%, with 100% of held-out values landing inside the 95% band.

+33%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 →
2.6Projected 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 →
0.61–4.595% 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 →
±56.2%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, Chimney Swift in Wisconsin is projected to rise about 33% by 2029 — from 1.9 in 2024 to a central estimate of 2.6 (95% range 0.61–4.5). A 5-year backtest shows a typical error of ±56.2%, 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 →
20252.70.774.7
20262.70.734.6
20272.60.694.6
20282.60.654.6
20292.60.614.5

Chimney Swift Survey Routes in Wisconsin

Routes recording Chimney Swift in Wisconsin.
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 →
Omro1620011966
Kiel1520221998
Stevens Pt1420131967
Manitowoc1320231966
N Freedom1220241966
Pt Washingtn1120241966
Cochrane1020241967
Grimms1020211998
Weyerhauser920241966
Stratford820241968
Fall River820241967
Raymond820241966
Gresham820241998
Mukwonago820041998
Mukwonago 2820242005
Dresser720231966
Rib Lake720231966
Eden720241967
Mount Horeb719901967
Prairie Du Chien720221998
Iron River620241967
Gilman620241966
Meridean620221999
Mather520211970
Briggsville520181999

Chimney Swift Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawyoming

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