_ u Auk, XV. Jan., 1898, py-/y~7 
The Fauna of Muskeget Island — A Protest. 
Editors of ‘The Auk’: — 
Dear Sirs: —In a recent paper on the Terns of Muskeget Island, 2 Mr. 
George H. Mackay records the extermination of a family of Short-eared 
Owls that had established themselves on the island during the summer 
2 Auk, XIV, pp. 380-390. October, 1897. 
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The veitebrate fauna of Muskeget may be roughly divided into two 
groups: 1 st, animals which there find conditions essentially normal and 
similar to those to which they are subjected throughout their range; 
and 2nd, animals which there find essentially abnormal conditions, that 
is, conditions which distinctly differ from those to which they are else- 
where exposed. 1 To the first class belong most of the breeding birds, 
among which may be mentioned : Sterna hirundo , .S', dougalli, S. fara- 
disaa, Lams atricilla , rEgialitis meloda, Actitis macularia, Agelaius 
fhieniceus , Sturnella magna, Ammodramus caudacutus , A. sandwichensis 
savanna, and Melosfiza fasciata . 2 The coast form of the common toad 
probably belongs also in this category. In the second class we find the 
two mammals of the island, a Vole and White-footed Mouse, and only one 
biid, the Short-eared Owl. It is t,o the members of the second class that 
the chief interest attaches, because they are rapidly undergoing modifica- 
tion to fit them to the needs of their peculiar environment, while no such 
process is taking place among the inhabitants of the island that find 
there their normal surroundings. The process of change has progressed 
furthest with the Vole, Microtus bre-weri (Baird), which is now so 
much differentiated as to be readily separable from the wide-ranging 
Microtus pennyslvanicus of Nantucket, Martha’s Vineyard and the 
adjacent mainland. The White-footed Mouse, Peromyscus leucofus 
(Rafinesque), is beginning to undergo a series of changes which if not 
interruped will doubtless eventually result in the formation of a new 
species. 3 A similar process would doubtless take place in the Owls if 
they were strictly protected and allowed to become firmly established on 
the island, for the bare glaring sand and scant vegetation among, which 
1 A similar classification could probably be made with the plants, but here 
the preponderance of the first class would be even greater than in the case of 
the land Vertebrates. 
2 This list is taken from a summary of the Muskeget fauna published in 
1896. Miller, Proc. Bost. Soc. Nat. Hist., XXVII, pp. 79-83. 
3 See Miller, Proc. Bost: Soc. Nat. Hist., XXVII, p. 80. 
