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Lower Colorado River Multi-Species Conservation Program Balancing Resource Use and Conservation

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Wildlife

      Information Article

Technology Sheds Light on the Mystery of Western Yellow-billed Cuckoo Migration

The wind is starting to bite, making us shiver. We bundle deeper into our jackets and look up toward the sun, hoping for a bit of warmth, and then catch a glimpse of birds soaring through the cerulean sky, heading south for the winter. Their destination, and the route they take to get there, is not easy to discover, especially when those birds are as secretive as the western yellow-billed cuckoo.

The Yellow-billed cuckoo - Photo by Southern Sierra Research Station
  The Yellow-billed cuckoo - Photo by Southern Sierra Research Station  

During the summer of 2014 and 2015, 14 western yellow-billed cuckoos were captured at the Palo Verde Ecological Reserve (PVER) along the lower Colorado River (LCR) near Blythe, California, and fitted with lightweight GPS tags.

Harness and antenna attached to yellow-billed cuckoo for long distance tracking during winter and migration. - Photo by Southern Sierra Research Station    Harness and antenna attached to yellow-billed cuckoo for long distance tracking during winter and migration. - Photo by Southern Sierra Research Station
  Harness and antenna attached to yellow-billed cuckoo for long distance tracking during winter and migration. - Photos by Southern Sierra Research Station  

Like the GPS on your phone, these tags record locations. When the birds returned to PVER the following two breeding seasons, seven were recaptured, and six of the tags were recovered.

The GPS tags recorded 33 locations. These recordings provide important information to what we know about the route western yellow-billed cuckoos take during fall and spring migration between their breeding sites along the LCR and their wintering habitat in South America.

Maps showing the locations of six yellow-billed cuckoos during migration and winter, 2014-2016.
  Maps showing the locations of six yellow-billed cuckoos during migration and winter, 2014-2016.  

The information from this work indicates that western yellow-billed cuckoos that breed on the LCR follow a loop migration pattern, flying south along the Pacific coast through Mexico and Central America and returning in the spring along a more easterly route through Yucatan, Coahuila and Chihuahua, Mexico.

Most of the wintering data show the birds in the Gran Chaco forest of central South America which spans eastern Bolivia, western Paraguay, northern Argentina, and a portion of the Brazilian states of Mato Grosso and Mato Grosso do Sul.

The GPS points also give us insights about risks they may face each year. During migration, the birds stopped to forage and rest. Of those stops, 33% of the locations recorded fell within conservation areas such as biosphere reserves, national parks, and wildlife refuges between PVER and South America. The other 67% recorded locations were on private land outside formal protection.

Explore our Yellow-billed cuckoo page for more information about this bird and LCR MSCP’s conservation efforts for this species. Our reports page also has more information.

Other information can be found in McNeil, S.E., D. Tracy, and C.D. Cappello. 2015. Loop migration by a western yellow-billed cuckoo wintering in the Gran Chaco. Western Birds 46:244–255.

Updated December 19, 2018