Chimney Swift
Chimney Swift has collapsed: down 75% on the route-weighted index since 1968.
About the Chimney Swift
A cigar-shaped aerial bird that spends almost its whole life airborne, the Chimney Swift roosts and nests in chimneys and has declined sharply as masonry chimneys disappear.
- Size
- 4.5–6 in long, about 0.8 oz (12–15 cm, 23 g)
- 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 2,620 Breeding Bird Survey routes across 40 states, most concentrated in the Appalachian Mountains.
- Family
- Apodidae · Aerial insectivores
- Conservation
- Vulnerable
Notable Chimney Swift Trends
Chimney Swift has collapsed in surveyed states: down 75% on the route-weighted index since 1968.
Chimney Swift Population Forecast
If the recent trend holds, Chimney Swift is projected to fall about 35% by 2029 — from 2.2 in 2024 to a central estimate of 1.5 (95% range 0.00–2.9). A 5-year backtest shows a typical error of ±15.1%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 1.9 | 0.41 | 3.4 |
| 2026 | 1.8 | 0.30 | 3.3 |
| 2027 | 1.7 | 0.18 | 3.2 |
| 2028 | 1.6 | 0.07 | 3.1 |
| 2029 | 1.5 | 0.00 | 2.9 |
Where the Chimney Swift Is Detected
BBS routes recording Chimney Swift, sized by most recent count.
Chimney Swift Population Trend by State
| Alabama | -70% | 1968 | 109 |
| Arkansas | -74% | 1969 | 59 |
| Colorado | -82% | 1970 | 8 |
| Connecticut | +34% | 1968 | 20 |
| Delaware | -41% | 1968 | 17 |
| Florida | -29% | 1968 | 104 |
| Georgia | -71% | 1968 | 109 |
| Illinois | -66% | 1968 | 105 |
| Indiana | -48% | 1968 | 69 |
| Iowa | -88% | 1969 | 39 |
| Kansas | -89% | 1969 | 62 |
| Kentucky | -82% | 1968 | 63 |
| Louisiana | -11% | 1969 | 99 |
| Maine | -56% | 1968 | 73 |
| Maryland | -35% | 1968 | 76 |
| Massachusetts | -56% | 1968 | 32 |
| Michigan | -22% | 1968 | 93 |
| Minnesota | -71% | 1969 | 75 |
| Mississippi | -77% | 1968 | 70 |
| Missouri | -88% | 1969 | 91 |
| Montana | -11% | 1990 | 3 |
| Nebraska | -57% | 1969 | 55 |
| New Hampshire | -62% | 1968 | 25 |
| New Jersey | -6% | 1968 | 41 |
| New York | -34% | 1968 | 124 |
| North Carolina | -59% | 1968 | 111 |
| North Dakota | -46% | 1969 | 15 |
| Ohio | -68% | 1968 | 89 |
| Oklahoma | -89% | 1969 | 67 |
| Pennsylvania | -36% | 1968 | 133 |
| Rhode Island | +144% | 1969 | 6 |
| South Carolina | -77% | 1968 | 51 |
| South Dakota | +48% | 1970 | 13 |
| Tennessee | -74% | 1968 | 55 |
| Texas | -83% | 1969 | 184 |
| Vermont | -77% | 1968 | 26 |
| Virginia | -61% | 1968 | 87 |
| West Virginia | -71% | 1968 | 62 |
| Wisconsin | -55% | 1968 | 96 |
| Wyoming | insufficient data | n/a | 4 |
Chimney Swift Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Prairie Potholes | -71% | 1969 | 70 |
| Boreal Hardwood Transition | -79% | 1968 | 102 |
| Lower Great Lakes / St. Lawrence Plain | -45% | 1968 | 83 |
| Atlantic Northern Forest | -60% | 1968 | 150 |
| Shortgrass Prairie | -50% | 1969 | 33 |
| Central Mixed Grass Prairie | -80% | 1969 | 116 |
| Edwards Plateau | -74% | 1970 | 19 |
| Oaks and Prairies | -87% | 1969 | 74 |
| Eastern Tallgrass Prairie | -77% | 1968 | 273 |
| Prairie Hardwood Transition | -47% | 1968 | 157 |
| Central Hardwoods | -83% | 1968 | 162 |
| West Gulf Coastal Plain / Ouachitas | -71% | 1969 | 108 |
| Mississippi Alluvial Valley | -35% | 1968 | 68 |
| Southeastern Coastal Plain | -63% | 1968 | 342 |
| Appalachian Mountains | -54% | 1968 | 396 |
| Piedmont | -58% | 1968 | 171 |
| New England / Mid-Atlantic Coast | -40% | 1968 | 161 |
| Peninsular Florida | -32% | 1968 | 60 |
| Tamaulipan Brushlands | -40% | 1970 | 24 |
| Gulf Coastal Prairie | -44% | 1969 | 44 |
Chimney Swift Conservation Status
Vulnerable
The IUCN Red List rates this species as Vulnerable. Our route-weighted index shows it down about 75% 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.