BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Field Sparrow

PasserellidaeForest birdsSpizella pusilla

Field Sparrow has collapsed: down 77% on the route-weighted index since 1968.

-77%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 →
2,338RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years 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 Field Sparrow

The Field Sparrow (Spizella pusilla) is a North American member of the New World Sparrows (Passerellidae). In this analysis it is grouped with the forest birds.

Size
4.5–7.5 in long (12–19 cm) — a small songbird (typical for the family)
Habitat
Woodlands and forest edges, including wooded suburbs and parks.
Diet
Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
Range
Recorded on 2,338 Breeding Bird Survey routes across 40 states, most concentrated in the Appalachian Mountains.
Family
Passerellidae · Forest birds

Notable Field 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 →

long arc declinecomputed 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 →

Field Sparrow has collapsed in surveyed states: down 77% on the route-weighted index since 1968.

Field Sparrow Population Forecast

If the recent trend holds, Field Sparrow is projected to fall about 72% by 2029 — from 2.6 in 2024 to a central estimate of 0.74 (95% range 0.00–3.3). A 5-year backtest shows a typical error of ±65.9%, with 100% of held-out values landing inside the 95% band.

-72%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 →
0.74Projected 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 →
0.00–3.395% 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 →
±65.9%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, Field Sparrow is projected to fall about 72% by 2029 — from 2.6 in 2024 to a central estimate of 0.74 (95% range 0.00–3.3). A 5-year backtest shows a typical error of ±65.9%, with 100% 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 →
20251.20.003.8
20261.10.003.7
20270.960.003.5
20280.850.003.4
20290.740.003.3

Where the Field Sparrow Is Detected

BBS routes recording Field Sparrow, sized by most recent count.

Field Sparrow Population Trend by State

Field 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 →
Alabama-72%196894
Arkansas-85%196955
Coloradoinsufficient datan/a5
Connecticut-96%196819
Delaware-54%196817
Florida-97%196821
Georgia-71%196897
Illinois-57%1968104
Indiana-55%196869
Iowa-52%196938
Kansas+13%196957
Kentucky-74%196864
Louisiana-91%196927
Maine-87%196843
Maryland-76%196876
Massachusetts-87%196829
Michigan-67%196891
Minnesota-9%196958
Mississippi-65%196846
Missouri-47%196995
Montana+326%197932
Nebraska+131%196962
New Hampshire-88%196825
New Jersey-69%196841
New York-56%1968122
North Carolina-75%196899
North Dakota-49%196927
Ohio-67%196889
Oklahoma-64%196967
Pennsylvania-62%1968136
Rhode Island-19%19686
South Carolina-90%196845
South Dakota-41%196940
Tennessee-56%196854
Texas-35%196999
Vermont-87%196826
Virginia-65%196884
West Virginia-49%196863
Wisconsin-73%196891
Wyoming+118%198625

Field Sparrow Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Field 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 →
Northern Rockies-36%19909
Prairie Potholes+39%196973
Boreal Hardwood Transition-64%196883
Lower Great Lakes / St. Lawrence Plain-61%196884
Atlantic Northern Forest-88%1968114
Badlands and Prairies+89%196977
Shortgrass Prairie-92%197021
Central Mixed Grass Prairie+14%1969112
Edwards Plateau+20%196919
Oaks and Prairies-85%196947
Eastern Tallgrass Prairie-48%1968276
Prairie Hardwood Transition-63%1968157
Central Hardwoods-69%1968166
West Gulf Coastal Plain / Ouachitas-96%196974
Mississippi Alluvial Valley-91%196833
Southeastern Coastal Plain-44%1968250
Appalachian Mountains-67%1968395
Piedmont-77%1968170
New England / Mid-Atlantic Coast-83%1968157
Tamaulipan Brushlands-35%19808
Gulf Coastal Prairie-47%19816

Field Sparrow Conservation Status

Our route-weighted index shows it down about 77% since 1968.

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