Brown-Headed Cowbird
Molothrus ater
Cowbirds are well known as nest, or brood parasites. Some theorists believe that Brown-Headed Cowbirds developed this practice when they followed the great bison herds as they migrated and roamed freely from present day Mexico to Canada. To keep up with the migration, these birds would deposit their eggs in other bird’s nests, depending on their victims to raise the cowbird’s young. Cowbird chicks develop much faster than that of their hosts, so the host’s offspring rarely survive. Some host species learned to abandon an infected egg clutch and start a fresh one on top of the one with cowbird eggs. Other species have not done so well, resulting in populations declines.
Brown-Headed Cowbirds range over most of the North American continent, migrating north as far as southern and western Canada in summer. Many of these birds remain year-round on the west coast, southwestern USA, northern Mexico, Texas and through the lower Mississippi Valley east to New England and southeastern USA to northern Florida. South Florida and southern Mexico normally see them only in winter.
It is easy to dislike cowbirds if we apply human values to their practices. When I’ve met them during my travels in the western USA, I’ve tried to remember than nature can be harsh, and my value system is irrelevant in the larger scheme of the natural world.

Brown-Headed Cowbird(Molothrus ater) |
Description: Female along Rockhouse Truck Trail near Clark Lake in the Anza Borrego State Park. San Diego County, California. |
Date Taken: 2013:04:27 7:49 |
Location:
Rockhouse Trail |
Camera Information: NIKON D3X, 800 mm, f/8.0, 1/1000 |
File Name: D3X5100-BrownHeadedCowBird |
© 2013 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Male along Rockhouse Truck Trail near Clark Lake in the Anza Borrego State Park. San Diego County, California. |
Date Taken: 2013:04:27 7:49 |
Location:
Rockhouse Canyon |
Camera Information: NIKON D3X, 800 mm, f/8.0, 1/400 |
File Name: D3X5108-BrownHeadedCowBird |
© 2013 Jack Daynes, shadeTree-Imaging |


Brown-Headed Cowbird(Molothrus ater) |
Description: Male along Rockhouse Truck Trail near Clark Lake in the Anza Borrego State Park. San Diego County, California. |
Date Taken: 2013:04:27 7:52 |
Location:
Rockhouse Trail |
Camera Information: NIKON D3X, 800 mm, f/6.3, 1/2500 |
File Name: D3X5139-BrownHeadedCowBird |
© 2013 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Female along Rockhouse Truck Trail near Clark Lake in the Anza Borrego State Park. San Diego County, California. |
Date Taken: 2013:04:27 7:54 |
Location:
Rockhouse Canyon |
Camera Information: NIKON D3X, 800 mm, f/6.3, 1/2000 |
File Name: D3X5147-BrownHeadedCowBird |
© 2013 Jack Daynes, shadeTree-Imaging |


Brown-headed Cowbird(Molothrus ater) |
Description: Female, near the feed lot outside of Red Rock, Arizona. |
Date Taken: 2008:11:29 13:13 |
Camera Information: NIKON D2X, 800 mm, f/6.3, 1/350 |
File Name: jcd3049BrownHeadedCowBird |
© 2008 Jack Daynes, shadeTree Imaging |


Brown-headed Cowbird(Molothrus ater) |
Description: Juvenile bird at a Dairy Farm, Valley Center, San Diego County, California. |
Date Taken: 2004:10:13 12:46 |
Camera Information: NIKON D1X, 800 mm, f/11.0, 1/500 |
File Name: JCD_1081BrownHeadedCowbird |
© 2004 Jack Daynes, shadeTree Imaging |


Brown-Headed Cowbird(Molothrus ater) |
Description: Bear River Migratory Bird Refuge, 17 miles west of Brigham City Utah. |
Date Taken: 2015:05:12 10:27 |
Location:
Bear River |
Camera Information: NIKON D3X, 800 mm, f/8.0, 1/1000 |
File Name: D3X1880-BrownHeadedCowBird |
© 2015 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Bear River Migratory Bird Refuge, 17 miles west of Brigham City Utah. |
Date Taken: 2015:05:12 10:42 |
Location:
Bear River |
Camera Information: NIKON D3X, 800 mm, f/8.0, 1/3200 |
File Name: D3X1951-BrownHeadedCowBird |
© 2015 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Where feeders are in place at the Visitor Center, local critters can be readily observed. Malheur NWR Headquarters in eastern Oregon. |
Date Taken: 2015:06:02 17:44 |
Location:
Visitor Center |
Camera Information: NIKON D3X, 800 mm, f/7.1, 1/1600 |
File Name: D3X7008-BrownHeadedCowBird |
© 2015 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: This Brown-Headed Cowbird male was looking to find a female so his genes would contribute to next generation of nest parasites. I drove for three plus hours to spend two lovely hours with these birds at the Cienega in Arivaca before turning onto my final leg of my homeward journey from my 2020 Texas adventure. |
Date Taken: 2020:05:27 9:29 |
Location:
Arivaca Cienega |
Camera Information: NIKON D5, 800 mm, f/8.0, 1/8000 |
File Name: BrownHeadedCowbird_D5X6330-Arivaca |
© 2020 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Yard birds in Aspendell are different than most folk's yard birds, but most folks don't have yards at over 8400 feet in the Eastern Sierras. Near Bishop California in Inyo County. |
Date Taken: 2017:07:19 11:08 |
Location:
Aspendell |
Camera Information: NIKON D5, 800 mm, f/8.0, 1/800 |
File Name: BrownHeadedCowBird_D5X0151-Aspendell |
© 2017 Jack Daynes, shadeTree-Imaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Rockhouse Truck Trail near Clark Lake in the Anza Borrego State Park. San Diego County, California. |
Date Taken: 2013:04:27 7:26 |
Location:
Rockhouse Canyon |
Camera Information: NIKON D3X, 800 mm, f/8.0, 1/2000 |
File Name: D3X5041-BrownHeadedCowBird |
© 2013 Jack Daynes, shadeTree-Imaging |


Brown-Headed Cowbird(Molothrus ater) |
Description: These critters can be readily observerd at the Malheur NWR Headquarters in eastern Oregon. |
Date Taken: 2015:06:02 18:06 |
Location:
Malheur NWR |
Camera Information: NIKON D3X, 800 mm, f/8.0, 1/800 |
File Name: D3X7024-BrownHeadedCowbird |
© 2015 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Near Oh Ridge Road at the north end of June Lake in California. |
Date Taken: 2016:05:08 16:47 |
Location:
June Lake |
Camera Information: NIKON D7200, 800 mm, f/8.0, 1/1250 |
File Name: D72-1805-BrownHeadedCowBird |
© 2016 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: In close company with a group of Yellow-Headed Blackbirds at Dirty Socks Spring at the southern edge of the Owens Lake Basin, between Lone Pine and Olancha. |
Date Taken: 2016:04:20 17:36 |
Location:
Dirty Socks Spring |
Camera Information: NIKON D7200, 800 mm, f/8.0, 1/1250 |
File Name: D728068-BrownHeadedCowBird |
© 2016 Jack Daynes, shadeTreeImaging.com |


Brown-Headed Cowbird(Molothrus ater) |
Description: Juvenile near the feed lot outside of Red Rock, Arizona. |
Date Taken: 2013:08:29 15:27 |
Location:
Red Rock Feed Lot |
Camera Information: NIKON D3X, 800 mm, f/8.0, 1/1000 |
File Name: D3X2525-BrownHeadedCowBird-Juvenile |
© 2013 Jack Daynes, shadeTreeImaging.com |

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