110 U. S. BUEEAU OF FISHERIES. 



EXTERMINATION OF PREDATORY ANIMALS AT BUREATj's STATIONS.* 



Birds. — Traps placed on small platforms on stakes driven around 

 the pond are used at a number of the bureau's stations for the capture 

 of kingfishers, but these as well as the fish hawk, heron, fish duck, 

 mud hen, water ouzel, and all other feathered enemies of fish life 

 can be successfully held in check by the use of firearms. 



Mink. — These animals may be taken either on land or in the water 

 by means of a trap set on a projecting point of the bank, or in the 

 water at places where the signs indicate that they come for fish. A 

 mink will wander all along the banks of a stream or pond, exploring 

 every nook, including all the little brooks and ditches emptying into 

 it. The traps are therefore often set on fallen trees or logs across 

 small streams. Bait is sometimes used. For this purpose the entrails 

 of a bird or other animal are more satisfactory than the whole body, 

 and a decayed fish is still better. Mink are believed to feed princi- 

 pally on fish. 



Frogs. — There is some doubt as to whether frogs eat live fish and 

 fish eggs. It is safe to say, however, that frogs under 1 year of age 

 are not detrimental to fish. Frogs may be dipped from a pond by 

 means of a net fastened to a long pole, or they may be killed by 

 spearing. 



Snakes. — ^Water snakes are perhaps the worst enemies of fish and 

 should be killed by whatever method possible. Their depredations 

 may be considerably lessened by keeping the ponds and streams clear 

 of brush and debris. 



Muskrats. — Trapping is the most practicable means of checking 

 the inroads of muskrats, and if persisted in by a, trapper of some 

 skill their depredations may b& stopped. For this purpose a No. 1 

 steel trap with a long chain of wire attached is the most suitable. It 

 is usually best to set it half an inch to an inch under water, below 

 the niches or shelves along the banks where the animals feed, as 

 will be indicated by remains of roots and partially eaten stems of 

 plants. The chain should be securely fastened to a stake driven 

 as far out in the water as possible. When set in shallow water, 

 the rat will be likely to twist off a leg and escape ; but if deep water 

 is accessible, it will try to escape by diving, and if there is plenty 

 of chain it will soon drown. The trap may also be set under water 

 in the trails or runways, on logs or boards sloping into the water, 

 in burrows in the banks, or on the bottom of the pond at the en- 

 trance to a burrow, under the nest chambers of the houses. It is 

 rarely necessary to bait the trap, though a slice of carrot or turnip 

 will sometimes attract the animals. Wliere they are numerous a, 

 gun may be used at first, but they soon become timid and distrust- 

 ful, making this impracticable. Poisoning arppears not to have been 

 resorted to in the case of muskrats, perhaps because of the attendant 

 danger to other animals and because the dead rats pollute the water. 



Turtles. — The most effective way of removing turtles from a pond 

 or lake is to draw off the water and collect them in hand nets. If 

 this is not practicable, a pole about the size of a telegraph pole may 

 be placed slantwise in the water, at a point where the depth is from 



♦Advice given here is not to be taken as authority for killing animals protected by 

 State laws. 



