PRELIMINARY LIST OF THE MAMMALS OF NEW YORK 281 
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, 
’98, 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. ‘lhe 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 
NORTHERN LIMIT SOUTHERN TIMIT 
ZON 
Omats Sum of normal mean |Normal mean tempera- 
daily temperatures} ture of six hottest 
above 6° c. (48° F.) consecutive weeks 
OC Cubs 2 Of One 
INROAG Sb Ss0coaceabouooDIEOB CCU OD CODHOGCODOdOOUdAl| boobobeG00 |! caboododoe 110 150 
IEICE OMEN sobonubcscocgaooodH s Wat ooooopdudedull yodos.osben al coodceodde 114 157.2 
Canadian ........ Hate Web ay tens cotete raven ehe Gove venleca cereals son] clave etcset iaseyen uit ene Sieerars 18 64.4 
UNFEVOSHKOI. SoShanacacogcoeeanndb00sbUnGDLUbODEK 5 500 10 000 22 71.6 
Uppervaustraleeesrececnceerer Seigdas Laeweceon 6400 - 11 500 26 78.8 
boner WS Me, psoocooca sscounoDooGb oocooDdGGNS 10 000 HS OOD. | soccasdane |] aasonccoa0 
UbxOy KE oe Sab eqnooncnbauseneodendpooUnGas soudd0 14 500 PIR ets Wao aacos Sham WoacoCoRosoe 
Within the limits of New York stite, 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 of 
ome of the highest Adirondack peaks. The data are at present insufficient. 
