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

Osprey Population Trend in Massachusetts

All statesGeneralists

Osprey in Massachusetts has surged: up 986% on the route-weighted index since 1993.

+986%Since 1993TrendPercent 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 →
15Routes 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 →
27YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Osprey 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 →

Osprey has surged in Massachusetts: up 985% on the route-weighted index since 1993.

Osprey Population Forecast in Massachusetts

If the recent trend holds, Osprey in Massachusetts is projected to fall about 27% by 2029 — from 0.93 in 2024 to a central estimate of 0.68 (95% range 0.30–1.1). A 5-year backtest shows a typical error of ±67.4%, with 40% 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 →
0.68Projected 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 →
0.30–1.195% 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 →
±67.4%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, Osprey in Massachusetts is projected to fall about 27% by 2029 — from 0.93 in 2024 to a central estimate of 0.68 (95% range 0.30–1.1). A 5-year backtest shows a typical error of ±67.4%, with 40% of held-out values landing inside the 95% band.19792029
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 →
20250.620.231.00
20260.630.251.0
20270.650.271.0
20280.670.291.0
20290.680.301.1

Osprey Survey Routes in Massachusetts

Routes recording Osprey 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 →
Wellfleet 2820242016
Newburyport520212007
Gay Head320241996
N Oxford220162009
Warren 2220242016
E Dennis120211986
Marion120231979
Wellfleet120072005
Prattville120162002
Littleton120242016
Mansfield120212021
Cape Cod Ns120072007
Belchertown120192019
Warren120012001
N. Andover120222016

Osprey Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakentuckylouisianamainemarylandmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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