Waterfowl 203 



been improving year by year. In 1930 the carp control is said to have been re- 

 laxed, whereupon a decline in vegetation and ducks was promptly felt. 



Introduction of carp was apparently the cause of the original decline and 

 carp control is evidently the cause of the present comeback. 



A similar sequence of apparent cause and effect is said to have taken place 

 in Lake Pomme de Terre, Stevens County, Minnesota. 



These instances of course do not prove that carp were the cause of decline in 

 duck foods everywhere, or that carp control can restore duck foods anywhere, 

 but they nevertheless constitute important evidence that restoration through carp 

 control is sometimes effective. 



Idle Marshlands. I gathered the very strong impression during the sur- 

 vey that two simultaneous and seemingly contradictory changes are in process. 



The first is a rapidly mounting concentration of waterfowl in the remaining 

 high-class or extra attractive marshlands. 



This shift toward concentration areas has been coincident with the virtual 

 abandonment of many second-class marshlands. These second-class marshlands 

 are either not used at all, or else they are used only to a limited extent at night, 

 or during the period of the main flights, or, more frequently still, they are aban- 

 doned in fall but used to a considerable degree in spring. 



The net result is that while possibly only 10 per cent of the original marsh- 

 lands remain in existence, possibly only five per cent are actually used to any ex- 

 tent. The remainder are in effect idle range, as far as the fall migration is con- 

 cerned, and also as far as breeding is concerned. 



The following instances are offered in support of these assertions. 



In northeastern Indiana there are about five counties dotted with numerous 

 small lakes which have the appearance of being excellent duck waters. Years ago 

 the shooting was good. Most of them are still used by ducks in spring, but there 

 is practically no breeding, and the fall shooting has deteriorated to practically a 

 mud hen proposition. Evidently these Indiana lakes are of second-rate attractive- 

 ness, and have become virtually idle through a combination of shrinking aggregate 

 duck population, and a process of "burning out" through constant over-shooting. 

 It is possible that the installation of refuges and the propagation of foods might 

 to some degree restore the fall flight, and also breeding birds. 



Ohio has some good marshes in the region of Sandusky Bay which still enjoy 

 a fall flight and a few breeding birds. The pothole lakes south of Akron, how- 

 ever, the five so-called "State Lakes" in central Ohio, and the bottoms of the Ohio 

 River, have all deteriorated to approximately the same status as the Indiana lakes. 

 The same remedies might furnish the basis for improvement. 



Wisconsin has hundreds of lakes, many with the appearance of good duck 

 waters, but only a dozen or two still enjoy regular duck shooting. The remainder 

 are virtually idle as breeders, and in fall have sunk to a mud hen status. 



Breeding Grounds. The average sportsman does not realize the 

 tremendous difference in breeding capacity (or attractiveness to breeding fowl) 



