MILLER : BEACH MOUSE OF MUSKEGET ISLAND. 
81 
the mice on the main island to have been due to some local cause 
rather than to severe weather or failure in the food supply which 
would affect all alike. Whatever may have exterminated Microtus 
breweri on Muskeget, it is certain that the animals were not there in 
July, 1892. Careful search over the whole island failed to reveal 
any trace of the mice, and as they live almost entirely on the sur¬ 
face during the summer they are then easily found. 
On South Point Island and Adams Island, which were cut off 
from Muskeget before the Life-Saving Station burned, there were, 
however, large and thriving colonies. There were no mice on 
Gravelly Island, where, Mr. Sandsbury told me, they had never, to 
his knowledge, occurred. The 28th of December, 1892, I spent on 
Muskeget and the neighboring islands. The mice were as numerous 
as before on South Point Island, but the colony on Adams Island 
had greatly diminished. In June, 1893, I again visited Muskeget, 
this time in company with Mr. Outram Bangs and Mr. Chas. F. 
Batchelder. We found that the Microtus colony on Adams Island 
mJ 
had entirely disappeared. On South Point Island, however, the 
mice were so abundant that in less than two hours we caught forty- 
three. After selecting as many as we wanted for specimens, we 
turned out twenty-six on Muskeget. Although I have not been at 
Muskeget since 1893, I have heard that the mice on the main island 
are increasing rapidly. Mr. Sandsbury has written several times to 
this effect, and Mr. W. Iv. Fisher collected two dozen specimens for 
the U. S. Department of Agriculture during July, 1895. Mr. Fisher 
found two colonies — both in clumps of beach plum bushes — one 
at the east end of the island, near the place where we liberated the 
mice in 1893, the other about a mile farther west. He also found 
that the species was extinct on South Point Island. 
The habits of the Muskeget beach mice have been modified to 
meet the needs of a life among coarse, loose sand, in which no 
extensive burrows can be made except during the brief and irregular 
periods in winter, when the surface is frozen. Throughout the 
greater part of the year the animals are exposed to the full force of 
the elements, their only natural protection being that furnished by 
the scant beach vegetation or by fragments of drift wood and wreck¬ 
age. Where the mice are abundant, a labyrinth of well beaten paths 
crosses the sand in every direction, and Avhen one of the animals is 
chased, he follows these runways aimlessly and helplessly, until 
exhausted or until he finds some place of refuge, perhaps in a tuft of 
