148 



NORTH AMERICAN FAUNA 66 



Vasquez (1956, p. 114), who collected the only Maryland record of 

 this species, says that no external measurements are available for the 

 specimen, but he does give the following cranial measurements for the 

 female: Condylobasal length 38.1; basilar length (of Hensel) 34.3; 

 mastoidal breadth 17.1 ; depth of skull at first molars 9.1. 



Habitat and habits. — ^This animal is most abundant in the northern 

 United States and Canada where it inhabits the deep spruce stands. 

 In the southern part of its range it is often encountered in brushy fields 

 and hedgegrows, and it is particularly fond of stone walls, where it 

 can elude its enemies and catch the small mammals and birds which 

 form its prey. 



This weasel generally does not make its own home, but prefers to 

 occupy the chambers of some other mammal, most often a chipmunk's 

 cavity beneath a stump or pile of rocks. Its nest is composed of fur and 

 feathers from the animals on which it feeds. 



According to Hamilton (1943, p. 136) all the evidence suggests 

 that these weasels mate in the early summer, and the fertilized eggs, 

 after undergoing a short development remain quiescent for several 

 months. Embryonic development continues in the late winter, and the 

 four to nine young are born usually in mid-April. Hamilton states 

 that the male weasel assists in bringing food to the young during their 

 infancy and that there is much evidence that weasels remain paired 

 throughout the year. 



Hamilton (1933b, p. 333) reports fall and winter food of 191 ermine 

 in New York State as composed of the following : Meadow mice 35.7 

 percent; undetermined mammals (principally mice) 16.3 percent; 

 short-tailed shrews 15.1 percent; white-footed mice 11.4 percent; rab- 

 bits 9.0 percent; long-tailed shrews 4.9 percent; rats 4.4 percent; and 

 chipmunks 3.6 percent. In addition, birds comprised some 2.1 percent, 

 and reptiles and amphibians 1,2 percent of the fall and winter food 

 of weasels (354 Mustela erminea and Mustela frenata) . 



Remarks. — This species has been recorded only once from Maryland. 

 Vazquez (1956, pp. 113-114) reports that a cat killed an ermine on the 

 heavily wooded grounds of the Honeywell School, 4 miles northwest 

 of Bethesda, Montgomery County, on 27 May 1954. Prior to this, 

 Maryland was considered far south of the normal range of the ermine, 

 and it is possible that the animal escaped from captivity. Vazquez 

 states that the coloration is peculiarly grayish, and that its cranial 

 measurements are slightly larger than those of female Mustela erminea 

 cicognanii and approach those of males of this race. The skin and skull 

 of the specimen are in Vazquez' private collection and I have not ex- 

 amined them. 



