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NORTH AMERICAN FAUNA 66 



thought the two sexes must represent distinct species. Since the female 

 long-tailed weasel is so small, it is possible to mistake her for an er- 

 mine, and due allowance must be made for sex when separating these 

 species on the basis of size. 



Measurements. — External measurements of 12 adult males from 

 various parts of Maryland are: Total length 382 (340-429) ; tail 131.6 

 (110-155) ; hind foot 48 ( 34-48). Seven females from various parts 

 of the State have the following external measurements. Total length 

 286.6 (253-315) ; tail 93.1 (80-122) ; hind foot 34 (32-38). 



Cranial measurements of 10 adult males from Laurel, Prince 

 Georges County, are: Basilar length 42.7 (40.8-44.3); zygomatic 

 breadth 25.6 (23.5-27.3) ; interorbital breadth 9.8 (9.0-10.8) ; mas- 

 toidal breadth 22.4 (21.4-24.0) . Cranial measurements of three adult 

 females from Laurel are: Basilar length 36.1, 36.4, 36.5; zygomatic 



breadth 21.5, 21.7, ; interorbital breadth 7.9, 9.1, 9.1; mastoidal 



breadth 18.9, 19.0, 18.2. 



Habitat and habits. — This weasel prefers bushy field borders, brush- 

 land, open woodland, and woodland bordering cultivated fields and 

 pastures. It is quite adaptable and willing to live in close proximity to 

 man as long as suitable prey is available. Recently, I found one dead on 

 a road in the middle of Kensington, Montgomery County, where the 

 only suitable habitat for some distance was the bushy area bordering a 

 railroad track that runs through the center of town. Uhler and Llewel- 

 lyn (1952, p. 81) report that during a study made at the Patuxent 

 Research Center in Prince Georges County, only four weasels were 

 taken in three trapping seasons. Of these, two were taken along hedge- 

 rows, one in upland forest, and one along the Patuxent River. In the 

 Bare Hills-Lake Roland area, Bures (1948, p. 66) thought these weasels 

 were quite rare at first. Subsequent investigation revealed, however, 

 that they were more common than he suspected, and that they range 

 throughout the area except for the marsh and Serpentine. He says that 

 they seem to use the railroad right-of-way as a natural highway regu- 

 larly; their mortality rate was high there, since an average of four 

 specimens a year were recorded killed by passing trains. In an area as 

 small as that in which Bures was working, this is a high number of 

 weasels. 



This species generally does not make its own burrow, but uses an 

 abandoned one of a chipmunk or mole. Sometimes it will utilize a hole 

 among rocks or under a stump. The nest center is usually filled with 

 grass and lined with fur and feathers from the weasel's prey. 



Mating in this species occurs in July and August. The gestation 

 period is very prolonged, averaging about 279 days, but as in the 

 ermine, the embryo remains quiescent throughout most of this period 

 and only begins to develop rapidly during the last 27 days. The young. 



