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Species · Delaware · BBS 2025 Release · 1966–2024

Glossy Ibis Population Trend in Delaware

All statesWetland birds

Glossy Ibis in Delaware has surged: up 468% on the route-weighted index since 1968.

+468%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 →
11Routes 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 →
42YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Glossy Ibis 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 →

Glossy Ibis has surged in Delaware: up 468% on the route-weighted index since 1968.

Glossy Ibis Population Forecast in Delaware

If the recent trend holds, Glossy Ibis in Delaware is projected to rise about 158% by 2027 — from 2.0 in 2022 to a central estimate of 5.2 (95% range 0.00–12). A 5-year backtest shows a typical error of ±851.3%, with 80% of held-out values landing inside the 95% band.

+158%Change by 2027TrendPercent 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 →
5.2Projected 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1295% 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 →
±851.3%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, Glossy Ibis in Delaware is projected to rise about 158% by 2027 — from 2.0 in 2022 to a central estimate of 5.2 (95% range 0.00–12). A 5-year backtest shows a typical error of ±851.3%, with 80% of held-out values landing inside the 95% band.19662027
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 →
20234.90.0011
20245.00.0012
20255.00.0012
20265.10.0012
20275.20.0012

Glossy Ibis Survey Routes in Delaware

Routes recording Glossy Ibis 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 →
Mt Pleasant7620161975
Bethany Bch5019891970
Georgetown1020222003
Frankford520072007
Milton520042004
Harrington420141971
Wilmington320091967
Dover119771972
Lowes Xrds119851966
Blackbird120181994
Pepperbox119991999

Glossy Ibis Population Trend in Other States

alabamaconnecticutfloridageorgialouisianamainemarylandmassachusettsnew-hampshirenew-jerseynew-yorknorth-carolinarhode-islandsouth-carolinasouth-dakotatexasvirginia

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