486 Roosevelt Wild Life Bulletin 



fliers that are easily water-trapped, is one of many instances of the 

 admirable provisions of nature. 



Indeed, this is carried still further at this period. At this time 

 the minute life of the shore waters, especially the shore diatoms, 

 flat-worms, chironomids, and the young stages of may-flies, stone- 

 flies and caddis-flies, receives a tremendous impulse and becomes 

 quite prominent. At this period also the young of trout, suckers 

 and other fish in the mountain streams can be found in the shore 

 pools and shallow rapids feeding on the minute organisms in these 

 places. Here lies the remarkable coincidence : the simultaneous 

 appearance and growth of fish fry and of a protected food supply 

 for its use. For the older trout are unable to get into these shallows, 

 which therefore offer both protection and food to the young fish 

 (figs. 119, 130). 



From the foregoing it is evident that there exist only two well- 

 marked periods in the annual cycle of mountain trout streams, 

 namely, a "water food" period covering nearly eleven months of the 

 year, and a "surface food" period, occurring during the summer, and 

 lasting from four to six weeks. This is the period when trout, as 

 anglers put it, "rise to bait." These same periods might also be 

 called flood and ebb periods, or flood and drought periods, from the 

 fact that high water lasts from October to July, while the ebb or 

 low water stage of the summer is really very brief. 



With the fall rains the brief low water stage ceases and the con- 

 ditions revert to those existing during winter and spring, and con- 

 tinue to the time of emergence described, that is, about the first week 

 of July. 



FEEDING HABITS OF THE TROUT 



From the examination of fish stomachs it is possible to deduce 

 much about the food habits of fish. First, fish wi'l take food that 

 is easily captured ; secondly, that which is accessible with difficulty ; 

 and lastly, strange and unxisual food. Of the food available in moun- 

 tain streams, stone-flies and may-flies are most easily obtained and 

 ■constitute the major portion of the food eaten. Here, too, the eggs, 

 fry and fingerlings should be listed, as fish are cannibals when oppor- 

 tunity offers ; and trout are no exception, but will eat other fisli 

 just as greedily as will bass. Caddis-flies, well protected by virtue 

 of their tough attached cases, and moreover, even more inaccessible 

 on account of the appressed structure of many cases, rank in the 

 second category, and for that reason constitute a much smaller item 

 of fish food than the other two groups of insects. However, they 



