NORTH AMERICA AND THE WEST INDIES 95 



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 Muske- 

 get 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. K. 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 Muskeget colonies have ap- 

 parently continued to flourish since their reintroduction, for as 

 lately as the summer of 1937 Donald R. Griffin obtained a few 

 specimens there. The island is now a reservation for nesting 

 terns and other birds and is provided with warden service 

 through part of the year. To this end, also, the chance intro- 

 duction of cats is especially guarded against, so that for the 

 present the outlook is bright that the mice will continue to 

 survive. But it is obvious that any important change in the 

 living conditions, the introduction of parasites or disease, or 

 the lessening of human guardianship may again imperil them. 

 Concerning the special habits of these mice, Miller (1896) 

 writes further that they have been "modified to meet the needs 

 of a life among coarse, loose sand, in which no extensive bur- 

 rows 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 wreckage. Where the mice are abundant, a labyrinth of 

 well beaten paths crosses the sand in every direction, and 

 when 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 Ammophila, or beneath the 

 stalks of a beach golden rod. Occasionally a mouse tries to 

 escape by entering a burrow among the roots of the beach 

 grass, but these tunnels always afford a very insecure protec- 

 tion as they are close to the surface and seldom extend more 

 than a few inches, or at most a few feet. The mice apparently 



