BirdAnalyst
Species · BCR 22 · BBS 2026 Release · 1966–2025

Henslow's Sparrow In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieGrassland birds

Henslow's Sparrow in Eastern Tallgrass Prairie has surged: up 87% on the route-weighted index since 1968.

+87%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 →
116Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

Henslow's Sparrow has surged in Eastern Tallgrass Prairie: up 87% on the route-weighted index since 1968.

Henslow's Sparrow In Eastern Tallgrass Prairie Population Forecast

If the recent trend holds, Henslow's Sparrow in Eastern Tallgrass Prairie is projected to fall about 13% by 2030 — from 0.30 in 2025 to a central estimate of 0.27 (95% range 0.15–0.38). A 5-year backtest shows a typical error of ±45.2%, with 80% of held-out values landing inside the 95% band.

-13%Change by 2030TrendPercent 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 →
0.27Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.15–0.3895% 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 →
±45.2%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, Henslow's Sparrow in Eastern Tallgrass Prairie is projected to fall about 13% by 2030 — from 0.30 in 2025 to a central estimate of 0.27 (95% range 0.15–0.38). A 5-year backtest shows a typical error of ±45.2%, with 80% of held-out values landing inside the 95% band.19662030
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 →
20260.250.140.36
20270.250.140.37
20280.260.140.37
20290.260.150.37
20300.270.150.38

Routes In Eastern Tallgrass Prairie

Routes recording Henslow's Sparrow in Eastern Tallgrass Prairie.
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 →
New HamptonMISSOURI242025
Kankakee SandsINDIANA72025
AldenILLINOIS42019
WilliamsburgIOWA42008
BudaILLINOIS32016
MilfordILLINOIS32013
HarristownILLINOIS32025
BarclayKANSAS32019
FrankfordMISSOURI32024
LucerneMISSOURI32025
KunkleOHIO32025
WayneILLINOIS22022
Bluff SpgsILLINOIS22022
SterlingILLINOIS22008
Grape CreekILLINOIS22005
HebronINDIANA21966
BrookvilleINDIANA21973
BedfordIOWA22013
BryantIOWA22025
West LibertyIOWA22017
College Spgs 2IOWA22008
FilleyMISSOURI22022
DanvilleMISSOURI22015
OhioMISSOURI22023
MadisonMISSOURI22024

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.