LIFE ZOXES OF NEW YORK STATE 



With reference to the distribution of plant and animal life in North 

 America, Dr C. Hart Merriam has proposed to divide the continent into 

 Boreal, Austral and Tropical "regions"' of which the first two are represented 

 in New York. He has further divided these regions into "zones" ;- the Boreal 

 region into the Arctic, Hudsonian and Canadian zones; and the Austral 

 region into the Transition, Upper Austral, and Lower Austral zones. These 

 zones of the Austral rcgi(.m are again divided into humid or eastern, and 

 arid or western faunal areas, the eastern subdivision of the Transition zone 

 being called the AUeghanian faunal area, and the eastern division of the 

 Upper Austral zone, the Carolinian faunal area. These terms are so well 

 recognized at the present time that they will be employed in this discus- 

 sion of bird distribution in New York, the Carolinian, the AUeghanian, 

 and the Canadian faunas, as well as a slight tinge of the Hudsonian, being 

 represented within the State. 



The limits of these zones, Dr Merriam determines by laws of temperature 

 control [loc. cit . p. 54]. Taking the "sum of normal mean daily tempera- 

 tures above 43°F. (6° C.)" as determining the northern limits of the respec- 

 tive zones, the plants and animals of the Lower iVustral require an annual 

 total of at least 18000° F. (10000° C), those of the Upper Austral 11500° F. 

 (6400° C), and those of the Transition 10000° F. (5500° C). "The sotith- 

 ward distribution is governed by the mean temperature of a brief period 

 during the hottest part of the year," the "normal mean temperature of 

 the six hottest consecutive weeks" furnishing a satisfactory basis of deter- 

 mination. Thus the southern limit of the Hudsonian is estimated to be 

 the isotherm for the six hottest weeks of 57.2° F. (14° C), while the southern 

 limit of the Canadian is found to be 64°. 4 F. (iS° C), of the Transition 

 7i°.6 F. (22° C), of the Upper Austral 78°.8 F. (26° C). The actual dis- 



'TheGeographicDistribution of Life in North America. Smithsonian Inst. Rep't, iSgr, p. 365-415. 

 'U. S. Dep't Agric. Biol. Sur., Bui. lo. 1S9S, p. 1S-31. 



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