Observations on the Life History of Ascaphus truei Stejneger

WE are glad to present in this number of COPEIA dedicated to Dr. Leonhard Stejneger a summary of our observations on the life history of the most primitive frog in America, a genus and species described by him thirty-two years ago. A full report of our observations together with illustrations are reserved for later publication. The field observations reported below were made during the summer of 1930 on the east slope of the Olympic Mountains, in the vicinity of Lake Cushman, Washington. A series of specimens, both adults and larvae, were shipped alive in iced containers across the continent to New York. There several pairs mated and it was interesting that the details of the mating process observed by one of us in the field and by the other in the laboratory were found to be alike. All the field observations were made by Putnam while the laboratory studies, including notes on the ovulation and early development of Ascaphus, were recorded by Noble. Ascaphus truei appears to be uniformly distributed throughout the area under consideration. Adults, as well as larvae, are found most frequently in the shallow mountain streams, the adults usually hiding beneath stones. At night the adults have been found to leave the stream and crawl about on the banks. During cool, wet weather, the adults leave the vicinity of streams for several have been captured at such times away from water. Conversely, during dry, warm weather, larger catches were made in the streams than at other times. At elevations from 200 to 3500 feet above sea level, adults and larvae appear to be confined to streams surrounded by forest. Removal of the timber by lumbering or by fire results in the disappearance of Ascaphus apparently on account of the increased temperature of the exposed stream bed. Above timber line streams containing Ascaphus may reach a maximum temperature of 160 C (August 27). Ascaphus does not appear in streams possessing a large amount of decaying vegetation or lacking exposed stones which provide areas of attachment for the tadpoles and recesses in which the adults may conceal themselves. The larvae are always found in running water. Both larvae and adults are rare in the larger streams, apparently because of the trout which are known to feed on them.