Bronzed Cowbird
Bronzed Cowbird has held roughly steady: up 5% on the route-weighted index since 1969.
About the Bronzed Cowbird
The Bronzed Cowbird (Molothrus aeneus) is a North American member of the Blackbirds & Orioles (Icteridae). In this analysis it is grouped with the generalists.
- Size
- 6.5–17 in long (16–43 cm) — a small to medium songbird (typical for the family)
- Habitat
- A broad range of open and wooded habitats, often near people.
- Diet
- An opportunistic mix of insects, seeds, fruit and scraps.
- Range
- Recorded on 147 Breeding Bird Survey routes across 7 states, most concentrated in the Chihuahuan Desert.
- Family
- Icteridae · Generalists
Notable Bronzed Cowbird Trends
No notable trend signals for Bronzed Cowbird. See the full index history below.
Bronzed Cowbird Population Forecast
If the recent trend holds, Bronzed Cowbird is projected to rise about 33% by 2029 — from 0.07 in 2024 to a central estimate of 0.09 (95% range 0.01–0.18). A 5-year backtest shows a typical error of ±61.5%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.10 | 0.01 | 0.18 |
| 2026 | 0.10 | 0.01 | 0.18 |
| 2027 | 0.09 | 0.01 | 0.18 |
| 2028 | 0.09 | 0.01 | 0.18 |
| 2029 | 0.09 | 0.01 | 0.18 |
Where the Bronzed Cowbird Is Detected
BBS routes recording Bronzed Cowbird, sized by most recent count.
Bronzed Cowbird Population Trend by State
| Arizona | -80% | 1970 | 29 |
| California | insufficient data | n/a | 2 |
| Florida | insufficient data | n/a | 2 |
| Louisiana | -35% | 1990 | 11 |
| Nebraska | insufficient data | n/a | 1 |
| New Mexico | -36% | 1992 | 9 |
| Texas | -6% | 1969 | 93 |
Bronzed Cowbird Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Shortgrass Prairie | +228% | 2007 | 12 |
| Edwards Plateau | +7% | 1978 | 9 |
| Oaks and Prairies | +177% | 1971 | 10 |
| Mississippi Alluvial Valley | -51% | 2001 | 8 |
| Sonoran and Mojave Deserts | -88% | 1970 | 13 |
| Sierra Madre Occidental | -72% | 1970 | 17 |
| Chihuahuan Desert | -52% | 1983 | 29 |
| Tamaulipan Brushlands | -20% | 1969 | 27 |
| Gulf Coastal Prairie | +131% | 1971 | 16 |
Bronzed Cowbird Conservation Status
Our route-weighted index shows it up about 5% since 1969.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.