VARIATIONP. OK G AKTER-SNAKES. 13 



small mammals, and fledgling birds. While in captivity it seems to 

 be impossible to get them voluntarily to eat dead food, but in the 

 wild state specimens of three species (sirtalis, radix, elegans) have 

 been observed to take frogs, small mammals, and birds that had been 

 dead for a considerable time. 



In the northern part of their range, where cold winters prevail, 

 they hibernate like other reptiles, usually passing the months of 

 December, January, February, and part of March in a dormant con- 

 dition. The actual time of hibernation is dependent upon the char- 

 acter of the weather, for a few warm days in January or February 

 is sufficient to bring them out. This was well illustrated in the winter 

 of 1906^ which was an exceptionally mild one, and garter-snakes 

 were recorded in southern Michigan (Washtenaw County) on Jan- 

 uary 22. At the approach of warm weather in the spring the garter- 

 snakes are among the first snakes to appear, and may soon be found 

 in numbers in the vicinity of marshes, ponds, and streams, feeding 

 voraciously upon frogs that are so abundant in such places at this time 

 of the year. 



But little is known regardino; the time of coition, but at least one 

 of the forms (siHaUs) is known to copulate in the spring, bringing 

 forth its young in July, August, and September, and, as the other 

 forms for which we have tlata also bear their broods at this time, the 

 supposition seems justifiable that copulation in most cases takes 

 place in the spring, notwithstanding the statement of Coues (1878, 

 278) that specimens of I'adix have been observed in coitu in Septem- 

 ber and October. In some instances, at least, they exhibit a grega- 

 rious tendency during the breeding season. In 1880, E. L. Ellicott 

 (1880, 206-207) reported having seen an aggregation, in the follow- 

 ing words: *'I personally had the pleasure of observing it twice, both 

 times very early in the spring, and in- localities which could be called 

 wilderness. I first saw such a bundle of snakes in the neighborhood of 

 Ilchester, Howard County, Maryland, on the stony bank of the Pa- 

 tapsco River, heaped together on a rock and between big stones. It was 

 a very warm and sunny location, where a human being would scarcely 

 disturb them. I reasoned that the warmth and silence of that 

 secluded place brought them together. Some hundreds of them 

 could be counted, and all of them I found in a very, lively state of 

 humor, hissing at me with threatening glances, with combined forces 

 and with such persistency that stones thrown upon them could not 

 stop them nor alter the position of a single animal. They would 

 make the proper movements and the stone would roll off; all the 

 snakes in this lump were common snakes (Eufaenia sirtalis L.)." 

 As Hay (1892 b, 528) remarks, "It is altogether probable that such 

 assemblages are determined partly by the sexual impulses," a view 

 that is confirmed by the fact that in the spring groups do apparently 



