BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Eurasian Tree Sparrow

PasseridaeGeneralistsPasser montanus

Eurasian Tree Sparrow has surged: up 589% on the route-weighted index since 1969.

+589%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 →
60RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Eurasian Tree Sparrow

The Eurasian Tree Sparrow (Passer montanus) is a North American member of the Old World Sparrows (Passeridae). In this analysis it is grouped with the generalists.

Size
5.5–7 in long (14–18 cm) — a small, stout songbird (typical for the family)
Habitat
A broad range of open and wooded habitats, often near people.
Diet
An opportunistic mix of insects, seeds, fruit and scraps.
Range
Recorded on 60 Breeding Bird Survey routes across 3 states, most concentrated in the Eastern Tallgrass Prairie.
Family
Passeridae · Generalists

Notable Eurasian Tree Sparrow TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Eurasian Tree Sparrow. See the full index history below.

Eurasian Tree Sparrow Population Forecast

If the recent trend holds, Eurasian Tree Sparrow is projected to fall about 26% by 2029 — from 0.07 in 2024 to a central estimate of 0.05 (95% range 0.02–0.08). A 5-year backtest shows a typical error of ±38.6%, with 40% of held-out values landing inside the 95% band.

-26%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 →
0.05Projected 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 →
0.02–0.0895% 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 →
±38.6%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, Eurasian Tree Sparrow is projected to fall about 26% by 2029 — from 0.07 in 2024 to a central estimate of 0.05 (95% range 0.02–0.08). A 5-year backtest shows a typical error of ±38.6%, with 40% 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 →
20250.050.020.08
20260.050.020.08
20270.050.020.08
20280.050.020.08
20290.050.020.08

Where the Eurasian Tree Sparrow Is Detected

BBS routes recording Eurasian Tree Sparrow, sized by most recent count.

Eurasian Tree Sparrow Population Trend by State

Eurasian Tree Sparrow population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Illinois+294%196945
Iowa14×20138
Missouri+21%20077

Eurasian Tree Sparrow Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Eurasian Tree Sparrow population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Eastern Tallgrass Prairie+707%196959

Eurasian Tree Sparrow Conservation Status

Our route-weighted index shows it up about 589% since 1969.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.