284 Union Bay 



due to brown rats which had come from a very small dump 

 situated at some distance. When the condition was corrected 

 at its origin, the difficulty stopped, but had remedies been 

 applied without an investigation much useless expense 

 would have occurred. 



In my years of marsh observation I have seen few cases of 

 predation or apparent predation which were clear and defi- 

 nite enough to justify immediate action. For example, the 

 crows come to the marsh each spring, and knowing their 

 sharpness and ability to take advantage of all food oppor- 

 tunities, I thought for some time that the birds annually 

 made a practice of raiding the nests of the tule wrens, the 

 redwings, and the flycatchers. One day I saw a crow carry- 

 ing a young tule wren. This isolated case was my only evi- 

 dence, but I could see no other reason for their activity at 

 that time of year. Then I noticed that there was a small but 

 constant mortality among the spawning carp. I saw some 

 crows feeding on one of the carcasses. Never again did I 

 witness further predation on the young marsh birds and so, 

 in spite of many regular visits, I am now uncertain whether 

 there is regular predation on the young of the small birds, 

 whether the crows are attracted by the dead carp, or whether 

 some other kind of food brings them. 



Such experience has taught me, as I think it has taught all 

 unprejudiced observers, that too-hasty action has no place 

 in wildlife management, and that all possible information 

 about any creature's habits must be collected and weighed 

 before any control is considered necessary and decided 

 upon. A classic story on this matter was told me by one of 

 the leading authorities in the field. It concerned a bass lake 

 in the northeastern part of the United States. One of its 

 owners advanced the seemingly logical theory that, since 

 the lake contained a limited amount of food available for 

 fish and since the owners were interested only in bass, the 

 obvious way to increase their number and size was to elimi- 



