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

Summer Tanager Population Trend in Delaware

All statesGeneralists

Summer Tanager in Delaware has surged: up 12× on the route-weighted index since 1973.

12×Since 1973TrendPercent 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 →
13Routes 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 →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Summer Tanager 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 →

Summer Tanager has surged in Delaware: up 12× on the route-weighted index since 1973.

Summer Tanager Population Forecast in Delaware

If the recent trend holds, Summer Tanager in Delaware is projected to fall about 24% by 2029 — from 1.8 in 2024 to a central estimate of 1.4 (95% range 0.35–2.4). A 5-year backtest shows a typical error of ±69.6%, with 0% of held-out values landing inside the 95% band.

-24%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 →
1.4Projected 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 →
0.35–2.495% 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 →
±69.6%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, Summer Tanager in Delaware is projected to fall about 24% by 2029 — from 1.8 in 2024 to a central estimate of 1.4 (95% range 0.35–2.4). A 5-year backtest shows a typical error of ±69.6%, with 0% 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 →
20251.30.252.3
20261.30.282.3
20271.30.302.3
20281.40.332.4
20291.40.352.4

Summer Tanager Survey Routes in Delaware

Routes recording Summer Tanager 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 →
Holleyville 2520242006
Milton 2420172017
Pepperbox 2420242017
Harrington220232002
Frankford220121966
Holleyville220041966
Millsboro220222017
Georgetown220221992
Frederica119951995
Dover119671967
Lowes Xrds119861975
Milton120121988
Pepperbox120161998

Summer Tanager Population Trend in Other States

alabamaarizonaarkansascaliforniafloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmississippimissourinebraskanevadanew-jerseynew-mexiconorth-carolinaohiooklahomapennsylvaniasouth-carolinatennesseetexasutahvirginiawest-virginiawisconsin

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