BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Glossy Ibis Population Analysis

ThreskiornithidaeWetland birdsPlegadis falcinellus

Glossy Ibis has edged down: down 17% on the route-weighted index since 1968.

-17%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 →
140RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
59Years 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 Glossy Ibis

The Glossy Ibis (Plegadis falcinellus) is a North American member of the Ibises & Spoonbills (Threskiornithidae). In this analysis it is grouped with the wetland birds.

Size
21.5–35.5 in long (55–90 cm) — a large wader (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 140 Breeding Bird Survey routes across 18 states, most concentrated in the Peninsular Florida.
Family
Threskiornithidae · Wetland birds

Notable Glossy Ibis TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Glossy Ibis. See the full index history below.

Glossy Ibis Population Forecast

If the recent trend holds, Glossy Ibis is projected to stay roughly flat through 2030, near 0.11 (95% range 0.01–0.22). A 5-year backtest shows a typical error of ±125.3%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2030TrendPercent 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 →
0.11Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.01–0.2295% 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 →
±125.3%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 is projected to stay roughly flat through 2030, near 0.11 (95% range 0.01–0.22). A 5-year backtest shows a typical error of ±125.3%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20260.110.000.22
20270.110.000.22
20280.110.000.22
20290.110.010.22
20300.110.010.22

Where the Glossy Ibis Is Detected

BBS routes recording Glossy Ibis, sized by most recent count.

Glossy Ibis Population Trend by State

Glossy Ibis 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 →
Alabamainsufficient datan/a1
Connecticutinsufficient datan/a2
Delaware+28%196811
Florida+234%196963
Georgia-97%19685
Louisianainsufficient datan/a8
Maineinsufficient datan/a2
Maryland+702%196813
Massachusettsinsufficient datan/a2
New Hampshireinsufficient datan/a1
New Jersey+606%197111
New York+64%19863
North Carolina-90%19706
Rhode Islandinsufficient datan/a2
South Carolina-1%19733
South Dakotainsufficient datan/a1
Texasinsufficient datan/a1
Virginia+44%19795

Glossy Ibis Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Glossy Ibis 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 →
Southeastern Coastal Plain-88%196822
New England / Mid-Atlantic Coast+110%196849
Peninsular Florida+195%196957

Glossy Ibis Conservation Status

Our route-weighted index shows it down about 17% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.