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

Alder Flycatcher Population Trend in Massachusetts

All statesAerial insectivores

Alder Flycatcher in Massachusetts has surged: up 737% on the route-weighted index since 1969.

+737%Since 1969TrendPercent 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 →
23Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Alder Flycatcher Trends in MassachusettsNotable 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 →

Alder Flycatcher has surged in Massachusetts: up 737% on the route-weighted index since 1969.

Alder Flycatcher Population Forecast in Massachusetts

If the recent trend holds, Alder Flycatcher in Massachusetts is projected to fall about 27% by 2029 — from 1.5 in 2024 to a central estimate of 1.1 (95% range 0.56–1.6). A 5-year backtest shows a typical error of ±24.7%, with 100% of held-out values landing inside the 95% band.

-27%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 →
1.1Projected 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 →
0.56–1.695% 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 →
±24.7%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, Alder Flycatcher in Massachusetts is projected to fall about 27% by 2029 — from 1.5 in 2024 to a central estimate of 1.1 (95% range 0.56–1.6). A 5-year backtest shows a typical error of ±24.7%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20251.00.511.5
20261.00.521.6
20271.10.531.6
20281.10.541.6
20291.10.561.6

Alder Flycatcher Survey Routes in Massachusetts

Routes recording Alder Flycatcher in Massachusetts.
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 →
Chesterfield820241967
Cummington720141968
Monterey620242021
Cummington 2620242015
Pittsfield320161972
Warren220081979
Wellfleet119871987
Ware River120221993
Newburyport120101994
Maynard119941994
Littleton120092007
Princeton119761971
E Pepperell119931976
Belchertown120221976
S Barre120241973
N Orange120241969
Cheshire119921969
Sheffield120131973
Gay Head120192002
Wellfleet 2120182018
Holden120161986
Warren 2120182011
Hancock120152001

Alder Flycatcher Population Trend in Other States

alaskaconnecticutidahoillinoisindianaiowamainemarylandmichiganminnesotamontananew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniasouth-dakotavermontvirginiawashingtonwest-virginiawisconsin

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