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

Grasshopper Sparrow Population Trend in Delaware

All statesGrassland birds

Grasshopper Sparrow in Delaware has surged: up 129% on the route-weighted index since 1968.

+129%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 →
17Routes 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 →
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 Grasshopper Sparrow Trends in DelawareNotable 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 →

Grasshopper Sparrow has surged in Delaware: up 129% on the route-weighted index since 1968.

Grasshopper Sparrow Population Forecast in Delaware

If the recent trend holds, Grasshopper Sparrow in Delaware is projected to fall about 19% by 2029 — from 4.6 in 2024 to a central estimate of 3.7 (95% range 1.7–5.7). A 5-year backtest shows a typical error of ±45.4%, with 20% of held-out values landing inside the 95% band.

-19%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 →
3.7Projected 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 →
1.7–5.795% 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 →
±45.4%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, Grasshopper Sparrow in Delaware is projected to fall about 19% by 2029 — from 4.6 in 2024 to a central estimate of 3.7 (95% range 1.7–5.7). A 5-year backtest shows a typical error of ±45.4%, with 20% 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 →
20253.51.55.5
20263.61.55.6
20273.61.65.6
20283.71.65.7
20293.71.75.7

Grasshopper Sparrow Survey Routes in Delaware

Routes recording Grasshopper Sparrow in Delaware.
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 →
Millsboro1220242017
Mt Pleasant720191966
Frederica520141966
Blackbird520241995
Holleyville 2520242006
Frankford420121966
Milton420161967
Pepperbox420081998
Harrington320231967
Milton 2320172017
Holleyville220041966
Wilmington120081967
Dover119791966
Lowes Xrds119771966
Bethany Bch119861969
Georgetown120191992
Pepperbox 2120242021

Grasshopper Sparrow Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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