CHECK-LIST OF COLORADO BIRDS 3i5 



76 L American robin. Merula migratoria. Summer 

 resident, but not common ; some interesting questions 

 arise in connection M'ith intermediate forms. 



76la. Western robin. Merula migratoria propinqua. 

 Abundant summer resident ; breeds from plains to timber- 

 line. 



765a. Greenland ■wheatear. Saxicola cexanthe leuco- 

 RHOA. European species ; a straggler taken at Boulder by 

 Minot. 



766. Bluebird. Sialia si a lis. Rare summer resident ; 

 west to base of Rockies. 



767a. Chestnut-backed bluebird. Sialia mexicaxa 

 bairdi. Summer resident ; not common ; western form, 

 coming east as far as Pueblo. 



768. Mountain bluebird. Sialia arctica. Abundant 

 summer resident ; breeds from plains to timber-line ; in 

 autumn roams uj) to at least 13,000 feet. 



