Fes., 1912. MammMats or ILLInois anD WISCONSIN — Cory. 249 
The Hudson Bay Jumping Mouse is found within our limits from 
northern Illinois northward throughout Wisconsin. I have examined 
specimens from Lake and Jo Daviess counties, Illinois, and from Vilas, 
Burnett, Marinette, Pierce, Dodge and Rock counties, Wisconsin. 
Hollister records it from Racine and Walworth counties (I. c., p. 140), 
and Jackson from Oneida County, Wisconsin, and it undoubtedly 
occurs throughout the state. 
This curious Mouse inhabits both fields and woodland and I have 
seen it in bogs, although on the whole it seems to like brush grown 
places along fences and bordering timber. It is well named, for, when 
frightened, it makes a series of surprisingly long jumps, a distance of 
ten feet at a single leap being by no means unusual, and to a person 
who sees one of these little animals for the first time, its activity is 
astonishing. Suddenly from almost under his feet it goes flying through 
the air, barely touching the ground before it is up again with the seem- 
ing resiliency of a rubber ball, and the next moment it has disappeared 
in the bushes. 
It makes a nest in burrows in the ground, under logs, and in hollow 
trees and stumps. In summer it also constructs a rounded nest which 
is concealed behind rocks or under bushes and thick grass. These 
nests are usually about 4 or 5 inches in diameter, the entrance being 
a hole at one side. The young are from 3 to 6 in number. This 
species hibernates in winter in this latitude. Preble states that during 
the cold weather they are generally found singly, although sometimes 
in pairs, in nests in holes in the ground, which vary from a few inches 
to three feet below the surface. He says, ‘‘They lie rolled up like a 
ball with the feet close together and the tail curled about them. If 
removed from the nest and subjected to a moderate degree of heat, 
they revive and in the course of a few hours move about freely, but 
generally resume their lethargic state if again exposed to cold. The 
pulse and respiration are very slow” (l.c., p. 9). He also states that 
these animals sometimes hibernate in a nest above ground. 
Kennicott says, ‘‘Dr Hoy informs me that when he was a boy, in 
digging out a rabbit in winter, he found a pair of this species in a state 
of profound torpor, exhibiting all the phenomena of perfect hibernation. 
They were in a large nest of leaves situated two or three feet below the 
surface” (J.c., p. 97). 
An interesting article on the hibernation of the Jumping Mouse in 
Indiana is given by Professor Sanborn Tenney.* He says, “On the 
18th of January of the present year (1872), I went with Dr. A. Patton 
of Vincennes, Indiana, to visit a mound situated about a mile or a mile 
* Amer. Nat., VI, 1872, p. 330. 
