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 74 THE CONDOR VoL. XI "Biological Survey of the San Francisco Moun- tain Region, Arizona," and is concerned in part with the same problems. In the introduction the author says: "The San Bernardino mountains proper con- stitute the largest high mountain group in southern California, and include the highest peak south of Mt. Whitney. The forested area is more extensive than elsewhere in southern California, and promised a more abundant fauna. Furthermore, the isolation' of this mountain group from any other of approxi- mately similar altitude afforded an attractive feature. My interest therefore centered in this region, and I carried on.' investigations, with the purpose of ascertaining the composi- tion of its fauna, and the local distribution of the component species." The scope of the report is fairly indicated by the table of contents which is as follows: (1) Introduction; Itinerary. (2) Life Zones of the Region, with lists of the plants belonging to each. (3) General Considerations: A discus- sion relating to bird population and the in- fluences modifying it. (4) Some plants of the Region: A list of important species with notes on their distribution. (5) The Birds: A list of 139 species found in the region with a de- tailed record of distribution in each case, ex- tended biographical accounts of many species, and critical notes on others. (6) The Mam- mals: A list of 35 species detected in the re- gion with statements of distribution, habits and measurements of specimens. (7) The Rep- tiles: A list of 20 species observed, with notes on food, habits and range. Four life zones are included in this region. The Lower Sonoran zone occupies the Mojave desert plateau to the north, and parts of the much lower San Bernardino valley and San Gbrgonio pass to the south. The Upper So- noran embraces the vast chaparral belt of the Pacific slope, as well as the pinyon belt of the desert slope. Next above comes the Transi- tion which comprises the major part of the considerable forested area, predominating above the 6500-foot contour. Finally, the Boreal occupies the highest parts of the region, largely above the 9000-foot contour. A colored map and profile of the mountains give an ex- cellent idea of the distribution of these life areas. The divisions of the Boreal into Canadian, HudsonJan and Alpine-Arctic were difficult to distinguish, and no great wonder for only three trees occur--Pinus murrayaria, P. flex- ills and Popls trernloides. Boreal islands of small area are usually difficult to subdivide in proportion as they are distant from some Boreal feeder of considerable extent, although of course aridity and unfavorable soil play a very important part in reducing boreal spe- cies. The paucity of species in the present instance is emphasized if comparison is made with the central Sierra Nevada, where the Canadian has in favorable localities 8 or 9 trees (4 or 5 characteristic) and the Hudsonian 5 or 6 (2 at least confined to that belt). If a connt of the shrnbs were taken the poverty of the San Bernardino Mountain flora would be even more evident. In the Sierra Nevada the shrubby plants are more valuable, sometimes, than trees for tracing zone boundaries in de- tail. In the San Bernardino mountains an upper and lower division of the. Transition seemed to be more easily distinguishable than the Canadian from Hndsonian, or the latter from Alpine-Arctic. Under "General Considerations" the author describes some of the influences which modify bird population. In July, when the season of scarcity arrives in the valleys on the advent of the summer drought, many birds that have raised broods in April, May and June, begin to migrate up the monntains, where the season of plenty is just beginning. The highlands are thus a ready refuge when the Upper and Lower Sonoran zones become comparatively barren under the July heat. "Without the monntains to accommodate the excess of bird population, which could not be supported in late summer on the withered lowlands, we would have far fewer birds in the spring." Both the residents and early summer visitants of the valleys, who have availed themselves of the hospitality of the mountains, return to the lowlands in the fall. The visitants thus become transients in the autunm before un- dertaking the southeastward migration to their winter habitat. To the regular summer residents of the mountainsthose which breed there and whose number is about doubled by the acces- sion of offspring---are added the hordes of smn- mer invaders, with their young, increasing the original population of the mountains at least four fold. The supply of food seemed bountiful enough for an even greater nmnber of birds. Since the aggregate population probably re- mains constant from year to year, the annual increase of about half a million (these figures being merely illustrative for the region under consideration) must succumb before the next nesting season. The determining factor, the author believes, is the food supply of the vari- ous species in their winter habitat, wherever that may be--either the mountains, in the case of the few permanent residents, or the lowlands in the case of the migratory forms. It is not possible in this short notice to advert to several filustrative examples, nor indeed to consider all the conclusions reached. The chapter is interesting and the points well taken. Perhaps the rarest find among the birds was a specimen of Otus qarnrneola idahoensis cap- tnred June 15, 1905, at Bluff Lake. ,Regls