Willow Flycatcher
Willow Flycatcher has increased: up 45% on the route-weighted index since 1968.
About the Willow Flycatcher
The Willow Flycatcher (Empidonax traillii) 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 1,780 Breeding Bird Survey routes across 44 states, most concentrated in the Appalachian Mountains.
- Family
- Tyrannidae · Aerial insectivores
Notable Willow Flycatcher Trends
No notable trend signals for Willow Flycatcher. See the full index history below.
Willow Flycatcher Population Forecast
If the recent trend holds, Willow Flycatcher is projected to rise about 15% by 2029 — from 0.67 in 2024 to a central estimate of 0.78 (95% range 0.56–0.99). A 5-year backtest shows a typical error of ±16.3%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.78 | 0.56 | 0.99 |
| 2026 | 0.78 | 0.56 | 0.99 |
| 2027 | 0.78 | 0.56 | 0.99 |
| 2028 | 0.78 | 0.56 | 0.99 |
| 2029 | 0.78 | 0.56 | 0.99 |
Where the Willow Flycatcher Is Detected
BBS routes recording Willow Flycatcher, sized by most recent count.
Willow Flycatcher Population Trend by State
| Alaska | insufficient data | n/a | 2 |
| Arizona | +114% | 1998 | 5 |
| Arkansas | insufficient data | n/a | 8 |
| California | -52% | 1971 | 72 |
| Colorado | -61% | 1970 | 41 |
| Connecticut | +30% | 1969 | 17 |
| Delaware | +63% | 1978 | 7 |
| Georgia | -64% | 1977 | 5 |
| Idaho | +112% | 1971 | 53 |
| Illinois | +5% | 1968 | 99 |
| Indiana | -10% | 1968 | 66 |
| Iowa | +13% | 1969 | 34 |
| Kansas | +24% | 1981 | 11 |
| Kentucky | +98% | 1970 | 24 |
| Maine | -80% | 1979 | 30 |
| Maryland | +239% | 1968 | 44 |
| Massachusetts | +404% | 1970 | 25 |
| Michigan | -61% | 1968 | 70 |
| Minnesota | +125% | 1969 | 51 |
| Missouri | +120% | 1970 | 39 |
| Montana | -17% | 1970 | 65 |
| Nebraska | +236% | 1979 | 35 |
| Nevada | +39% | 1999 | 12 |
| New Hampshire | +205% | 1975 | 21 |
| New Jersey | +78% | 1970 | 28 |
| New Mexico | -50% | 1973 | 12 |
| New York | +113% | 1968 | 113 |
| North Carolina | +0% | 1971 | 12 |
| North Dakota | +171% | 1969 | 48 |
| Ohio | +36% | 1968 | 84 |
| Oklahoma | -50% | 1975 | 10 |
| Oregon | -78% | 1970 | 98 |
| Pennsylvania | +96% | 1968 | 118 |
| Rhode Island | +15% | 1987 | 4 |
| South Dakota | +179% | 1969 | 33 |
| Tennessee | -29% | 1970 | 15 |
| Texas | insufficient data | n/a | 1 |
| Utah | -22% | 1974 | 38 |
| Vermont | +100% | 1977 | 24 |
| Virginia | -65% | 1969 | 33 |
| Washington | -65% | 1970 | 93 |
| West Virginia | -23% | 1968 | 50 |
| Wisconsin | +114% | 1968 | 77 |
| Wyoming | -38% | 1970 | 53 |
Willow Flycatcher Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Northern Pacific Rainforest | -66% | 1970 | 105 |
| Great Basin | -61% | 1970 | 118 |
| Northern Rockies | -41% | 1970 | 157 |
| Prairie Potholes | +144% | 1969 | 89 |
| Boreal Hardwood Transition | -68% | 1975 | 43 |
| Lower Great Lakes / St. Lawrence Plain | +67% | 1968 | 84 |
| Atlantic Northern Forest | +432% | 1968 | 89 |
| Sierra Nevada | -86% | 1974 | 13 |
| Southern Rockies / Colorado Plateau | +4% | 1970 | 79 |
| Badlands and Prairies | +279% | 1970 | 54 |
| Central Mixed Grass Prairie | +349% | 1983 | 23 |
| Eastern Tallgrass Prairie | -29% | 1968 | 225 |
| Prairie Hardwood Transition | +19% | 1968 | 152 |
| Central Hardwoods | +211% | 1968 | 71 |
| Mississippi Alluvial Valley | -47% | 1988 | 7 |
| Appalachian Mountains | +82% | 1968 | 271 |
| Piedmont | +65% | 1968 | 54 |
| New England / Mid-Atlantic Coast | +275% | 1968 | 86 |
| Coastal California | +11% | 1972 | 29 |
| Sonoran and Mojave Deserts | -9% | 1973 | 8 |
Willow Flycatcher Conservation Status
Our route-weighted index shows it up about 44% 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.