BirdAnalyst
Species · BCR 22 · BBS 2025 Release · 1966–2024

Henslow's Sparrow In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieGrassland birds

Henslow's Sparrow in Eastern Tallgrass Prairie has risen sharply: up 71% on the route-weighted index since 1968.

+71%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 →
114Routes 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 →
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 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 risen sharply in Eastern Tallgrass Prairie: up 71% on the route-weighted index since 1968.

Forecast

If the recent trend holds, Henslow's Sparrow in Eastern Tallgrass Prairie is projected to rise about 53% by 2029 — from 0.17 in 2024 to a central estimate of 0.26 (95% range 0.14–0.37). A 5-year backtest shows a typical error of ±44.8%, with 80% of held-out values landing inside the 95% band.

+53%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 →
0.26Projected 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 →
0.14–0.3795% 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 →
±44.8%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 rise about 53% by 2029 — from 0.17 in 2024 to a central estimate of 0.26 (95% range 0.14–0.37). A 5-year backtest shows a typical error of ±44.8%, with 80% 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 →
20250.240.130.35
20260.240.130.36
20270.250.140.36
20280.250.140.37
20290.260.140.37

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 →
LucerneMISSOURI62021
AldenILLINOIS42019
WilliamsburgIOWA42008
SticklervillMISSOURI42024
BudaILLINOIS32016
MilfordILLINOIS32013
Kankakee SandsINDIANA32024
BarclayKANSAS32019
FrankfordMISSOURI32024
WayneILLINOIS22022
FairburyILLINOIS22023
Bluff SpgsILLINOIS22022
SterlingILLINOIS22008
Grape CreekILLINOIS22005
HebronINDIANA21966
W LafayetteINDIANA22024
BrookvilleINDIANA21973
BedfordIOWA22013
West LibertyIOWA22017
College Spgs 2IOWA22008
FilleyMISSOURI22022
DanvilleMISSOURI22015
OhioMISSOURI22023
MadisonMISSOURI22024
TrentonMISSOURI22019

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