| Recent miniaturization of GPS devices enables studying passerine migration with unprecedented precision. Black-headed Grosbeak (Pheucticus melanocephalus) is a molt-migrating species documented to undergo its prebasic molt during fall in the North American Monsoon region of the southwestern United States and northwestern Mexico. During June 2014 we GPS-tagged nine adult Black-headed Grosbeaks in Yosemite National Park with Lotex Pinpoint-8 archival gps tags. In June 2015 one of these birds was recaptured with its GPS unit still attached. By August 20, 2014, the bird had traveled 1,300 km to Sonora, Mexico. It remained there until November, when it flew 1,324 km to the Michoacan-Jalisco border, where it remained until the last coordinates were collected on March 24, 2015. These data are consistent with the expected seasonal timing and duration of a molt-migrating bird, and represent the first time breeding, molting, and wintering sites have been identified with this level of precision in a western Neotropical migrant. Remote-sensed Enhanced Vegetation Index (EVI) data revealed that the grosbeak arrived in the monsoon region just after the EVI reached its peak, and then departed as the index declined, suggesting a possibly delicate match between migration timing and monsoon-driven phenology that warrants further study. |