Today, I found a male Lucy's Warbler in Rabbit Valley about a mile from the Utah Border in Mesa County, Colorado. This warbler, the smallest of the wood warblers in North America and one of only two to nest in trees, is extremely rare and localized in Colorado, regularly occurring only in Yellowjacket Canyon in Montezuma County, Colorado, in the Southwest corner of the state. In addition to these and the one observed today, there are (to my knowledge) four records of this warbler in Colorado; the first being an adult male singing in downtown Grand Junction, Mesa County in May 1991, another being observed in Lamar, Prowers County, another in eastern Colorado (location?), and finally an adult male in Gateway, Mesa County in April of last year (found the 24, I saw this bird on the 27). The fact that three records have come from Mesa County, and that two of them have occured each of the past two springs suggests that this bird may be becoming more regular on the Dolores and Colorado Rivers near the Utah border. It will be interesting to see what the future brings.
Lucy's Warbler is distinguished from other Vermivora warblers by having a plain, grayish overall look with a chestnut/rusty rump and crown, and faint eyeline.