PRELIMINARY LIST OF THE MAMMALS OF NEW YORK 



28l 



dependent on the extent of the " island Thus the Hudsonian area in 

 northern New York, while large enough to support a characteristic flora, 

 is apparently too small to be inhabited by any typical Hudsonian 

 assemblage of mammals. Effects similar to those of elevation are pro- 

 duced by isolated swamps (see Bailey '96, p. 250-51 and Batchelder, '96a, 

 p. 192-93) and cold rock slides (see Batchelder, '96a, p. 188 and Miller, 

 798, p. 615-18). The reverse condition of a southern island in a more 

 northerly zone is less frequently met with though it occasionally occurs. 



In North America seven life zones are represented. These are 

 (beginning at the north) the Arctic, Hudsonian, Canadian, transition, 

 upper austral, lower austral and tropical. The temperatures limiting 

 these life areas are tabulated as follows, by Merriam ('94, p. 237, '98, 

 p. 55). It is to be noticed that the northern limit of each zone is 

 determined by an isotherm representing the sum of the positive tem- 

 peratures for the entire season of growth and reproduction, and that 

 the southward distribution is governed by the mean temperature of a 

 brief period during the hottest part of the year, (Merriam, '94. p. 237, 

 '98, p. 54). 



Governing temperatures 



Arctic 



Hudsonian 



Canadian 



Transition 



Upper austral. 

 Lower austral, 

 Tropical 



ZONES 



NORTHERN LIMIT 



SOUTHERN 1 1 MIT 



Sum of normal mean Normal mean tempera- 

 daily temperatures ture of six hottest 

 above 6° c. (43° F.) I consecutive weeks 



C. 



5 500 



6 400 

 10 000 

 14 500 



10 000 



11 500 



18 oon 



26 000 



' c. 



M0 

 M4 

 18 

 22 

 26 



° F. 



»50 



1 57.2 

 64.4 

 71.6 



Within the limits of New York state, with its north and south extent 

 of only 260 miles, the irregularities of surface are such that no less than 

 four life zones are represented. 1 The areas that they occupy within the 

 state are briefly as follows : 



Hudsonian : Summits of the highest Adirondacks (and possibly of 

 the Catskills also) above the region of perfect forest 

 growth. 



Canadian : Adirondack forest region, and many ' islands ' on hilltops 

 to the southward, specially in the Catskills. 



1 Estimated from insufficient data. 



2 It is probable that a fifth, the Arctic, should be recognized as occupying the treeless summits or 

 some of the highest Adirondack peaks. The data are at present insufficient. 



