556 



////•; AMERICAN NATURALIST 



[Vol. LIV 



Winter Habits 



The habits of Fundulus heteroclitus in the ocean in winter are 

 not fully known. The late Vinal Edwards of the U. S. Bureau 

 of Fisheries, Woods Hole, Mass., stated to the writer that it was 

 his observation that they spend a large part of the winter near 

 the mouths of rivers in water which is moving and which is at a 

 salinity slightly lower than that of the sea. 



In November, when the temperature of the water on the 

 marshes goes down to 40° F., the migration inland is much re- 

 duced. Field observations showed that fish in temporary pools 

 at this time attempted to burrow in the bottoms and being of 

 course unsuccessful on account of the hardness of the clay died 

 during the night as the temperature went down to nearly the 

 freezing point. In the case of permanent pools whose bottoms 

 were covered with soft mud, the fish burrowed down during the 

 night and emerged when the sun came out and warmed the water. 



At about the time that ice begins to form over the permanent 

 pools, migration ceases so far as the marshes are concerned. In 

 the pools, fish were found burrowed in the mud at a depth of 

 from 6 to 8 inches in the middle i»f tin' winter. The temperature 

 of the mud was from 40° F. to 45° F. and that of the water 

 ranged from 32° F. to above 40° F., even in February, since the 

 shallower pools were warmed considerably by the sun. On 

 bright days when the sun was most effective, a few hardy fish 

 ventured forth from hibernal ion and swam slowly around under 

 the ice, feeding but little. Associated with them were shrimps, 

 myriapods. eels and another minnow {Cyprinodon var.), all of 

 which were burrowed in the mud during mast of the winter. 



Examinations of the stomach contents of Fundulus showed 

 that the food during the winter was largely algal matter in those 

 individuals that became active. By far the majority of the fish 

 remained torpid until early spring, beginning to feed again in 

 March, and tvassuming complete activity early in April. 



Summary 



2. Spring migration be; 

 by several factors, includ 

 land water; currents due 



