BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Alder Flycatcher

TyrannidaeAerial insectivoresEmpidonax alnorum

Alder Flycatcher has surged: up 178% on the route-weighted index since 1968.

+178%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 →
786RoutesSurvey 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 Alder Flycatcher

The Alder Flycatcher (Empidonax alnorum) is a North American member of the Tyrant Flycatchers (Tyrannidae). In this analysis it is grouped with the aerial insectivores.

Size
4.5–9 in long (12–23 cm) — a small to medium flycatcher (typical for the family)
Habitat
Open airspace over fields, water and towns; nests in cavities, earthen banks or on structures.
Diet
Flying insects caught on the wing.
Range
Recorded on 786 Breeding Bird Survey routes across 26 states, most concentrated in the Atlantic Northern Forest.
Family
Tyrannidae · Aerial insectivores

Notable Alder Flycatcher 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 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 →

Alder Flycatcher has surged in surveyed states: up 178% on the route-weighted index since 1968.

Alder Flycatcher Population Forecast

If the recent trend holds, Alder Flycatcher is projected to rise about 35% by 2029 — from 0.86 in 2024 to a central estimate of 1.2 (95% range 0.81–1.5). A 5-year backtest shows a typical error of ±32.7%, with 80% of held-out values landing inside the 95% band.

+35%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 →
1.2Projected 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 →
0.81–1.595% 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 →
±32.7%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, Alder Flycatcher is projected to rise about 35% by 2029 — from 0.86 in 2024 to a central estimate of 1.2 (95% range 0.81–1.5). A 5-year backtest shows a typical error of ±32.7%, with 80% 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 →
20251.10.761.5
20261.10.781.5
20271.10.791.5
20281.20.801.5
20291.20.811.5

Where the Alder Flycatcher Is Detected

BBS routes recording Alder Flycatcher, sized by most recent count.

Alder Flycatcher Population Trend by State

Alder Flycatcher 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 →
Alaska-27%1975114
Connecticut+66%197613
Idahoinsufficient datan/a1
Illinoisinsufficient datan/a2
Indiana-53%19858
Iowainsufficient datan/a2
Maine-45%196877
Maryland-21%19785
Massachusetts+737%196923
Michigan+224%196989
Minnesota+71%196962
Montanainsufficient datan/a6
New Hampshire+13%196826
New Jersey-10%19877
New York+612%1968105
North Carolinainsufficient datan/a3
North Dakota-1%198113
Ohio-82%197516
Oklahomainsufficient datan/a1
Pennsylvania+287%197378
South Dakotainsufficient datan/a1
Vermont+242%196825
Virginiainsufficient datan/a1
Washingtoninsufficient datan/a1
West Virginia+282%198016
Wisconsin+77%196891

Alder Flycatcher Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Alder Flycatcher 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 →
BCR 2-87%199317
BCR 4-36%197668
Northern Pacific Rainforest-21%198426
Prairie Potholes-63%197724
Boreal Hardwood Transition+125%1968121
Lower Great Lakes / St. Lawrence Plain+429%196969
Atlantic Northern Forest+55%1968153
Eastern Tallgrass Prairie+63%199211
Prairie Hardwood Transition+35%1968113
Appalachian Mountains+507%1970133
New England / Mid-Atlantic Coast+95%197135

Alder Flycatcher Conservation Status

Our route-weighted index shows it up about 178% since 1968. Aerial insectivores have fallen sharply across the continent, a decline widely linked to dwindling insect prey.

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