BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Least Flycatcher

TyrannidaeAerial insectivoresEmpidonax minimus

Least Flycatcher has fallen sharply: down 55% on the route-weighted index since 1968.

-55%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 →
1,185RoutesSurvey 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 Least Flycatcher

The Least Flycatcher (Empidonax minimus) 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 1,185 Breeding Bird Survey routes across 38 states, most concentrated in the Appalachian Mountains.
Family
Tyrannidae · Aerial insectivores

Notable Least 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 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 →

Least Flycatcher has fallen sharply in surveyed states: down 55% on the route-weighted index since 1968.

Least Flycatcher Population Forecast

If the recent trend holds, Least Flycatcher is projected to fall about 37% by 2029 — from 0.63 in 2024 to a central estimate of 0.39 (95% range 0.19–0.60). A 5-year backtest shows a typical error of ±27.6%, with 60% of held-out values landing inside the 95% band.

-37%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 →
0.39Projected 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 →
0.19–0.6095% 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 →
±27.6%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, Least Flycatcher is projected to fall about 37% by 2029 — from 0.63 in 2024 to a central estimate of 0.39 (95% range 0.19–0.60). A 5-year backtest shows a typical error of ±27.6%, with 60% 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 →
20250.460.250.66
20260.440.230.65
20270.420.220.63
20280.410.200.61
20290.390.190.60

Where the Least Flycatcher Is Detected

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

Least Flycatcher Population Trend by State

Least 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-23%19939
Arkansasinsufficient datan/a1
Californiainsufficient datan/a1
Coloradoinsufficient datan/a3
Connecticut-84%196820
Georgiainsufficient datan/a2
Idaho+170%199114
Illinois-82%197030
Indiana-75%197119
Iowa-4%197023
Kentuckyinsufficient datan/a2
Maine-60%196878
Maryland-75%196814
Massachusetts-25%196826
Michigan+2%1968103
Minnesota+25%196986
Missouriinsufficient datan/a1
Montana+821%197179
Nebraskainsufficient datan/a4
New Hampshire-79%196826
New Jersey-52%196914
New York-63%1968122
North Carolina-72%197514
North Dakota+257%196951
Ohio-67%196840
Oregoninsufficient datan/a2
Pennsylvania-41%1968111
Rhode Island-91%19684
South Carolinainsufficient datan/a1
South Dakota+157%196932
Tennessee+58%19697
Utahinsufficient datan/a2
Vermont-46%196826
Virginia-69%197025
Washington-37%198616
West Virginia+573%196846
Wisconsin-29%196897
Wyoming+110%197734

Least Flycatcher Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Least 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 →
Northern Pacific Rainforest+178%19955
Great Basin-55%199017
Northern Rockies+590%197278
Prairie Potholes+193%196995
Boreal Hardwood Transition-20%1968127
Lower Great Lakes / St. Lawrence Plain-61%196883
Atlantic Northern Forest-67%1968156
Southern Rockies / Colorado Plateau-69%19945
Badlands and Prairies+380%196969
Eastern Tallgrass Prairie-71%196966
Prairie Hardwood Transition-27%1968143
Appalachian Mountains-45%1968257
Piedmont-85%196918
New England / Mid-Atlantic Coast-85%196852

Least Flycatcher Conservation Status

Our route-weighted index shows it down about 55% 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.