1914 BIRDS OF ARIZONA 93 



Species ix the Transition Zone and Higher, more nearly Related to the 

 Mexican Plateau Fauna to the Southward. 



SUMMER VISITANT 



1. Otus trichopsis 8. Myiochanes p. pallidiventris 



2. Otus flammeolus 9. Empidonax f. pygmaeus 



3. Trogon ambiguus 10. Piranga hepatica 



4. Antrostomus v. macromystax 11. Dendroica a. nigrifrons 



5. Eugenes fulgens 12. Setophaga picta 



6. Cyanolaemus clemencia? 13. Cardellina rubrifrons 



7. Myiodynastes luteiventris 14. Certhia f. albescens 



RESIDENT 



1. Cyrtonyx m. montezumae 4. Junco p. dorsalis 



2. Meleagris g. merriami 5. Peucedramus olivaceus 

 .1 Junco p. palliatus 6. Penthestes sclateri 



Dividing the sixty species occurring in the Transition zone and higher into 

 two groups we find that there are forty which are the same as, or closely related 

 to, species occurring to the northward, in the Rock}- Mountains or in the Sierra 

 Nevada of California, and twenty which ere the same as, or most closely related 

 to, Mexican forms. 



Many of the first mentioned group find their southern limit in northern or 

 central Arizona, some extend to southern Arizona, and abor.t half the list occur 

 southward onto the plateau region of northern Mexico. A division of this group 

 into summer visitants and residents results in thirteen of the former and twenty- 

 seven of the latter. From these relative numhers it is evident that the birds of 

 the high mountains of northern and central Arizona are mostly species at the 

 southernmost extension of their range-, indicating, in fact, the southern limit of 

 the Rocky Mountain avifauna. 



Now turning to the species of Mexican affinities we find conditions reversed, 

 in that of the twenty forms listed, fourteen are summer visitants, while only six 

 are resident. These birds, of tropical derivation, are here at their northernmost 

 limits, and but a small proportion of them can endure the winter climate of this 

 latitude. Of the fourteen summer visitants all but one extend only into the south- 

 ern half of Arizona, many of them but an extremely short distance north of the 

 southern boundarv of the state. 



A great difference in the bird life of the higher zones of northern and 

 southern Arizona is that while in the former region a great part of the popula- 

 tion is resident, in the latter most of the species depart during the winter months. 

 The highest parts of the mountains of southern Arizona are noticeably deficient 

 of bird life in winter, and many of the birds seen at this time belong to species 

 nesting farther north in the state, which occur here in winter only. 



In general it may be said of the avifauna of the high mountains of Arizona, 

 that the ranges of the northern part of the state are more nearly like the Rocky 

 Mountains to the northward, and the northern Sierra Nevada, while the southern 

 mountain chains bear a somewhat closer resemblance to the mountains of south- 

 ern California. In the northern and central parts of the state we find such species 

 as Dendragaptts obscurus, Picoides a. dorsalis, Perisoreirs c. capitalis, Zonotrichia 



