COMMON MALLARD 



155 



those ducks which are prone 4o gorge themselves on the rotting flesh of 

 salmon in the rivers of the Northwest. 



Referring to acorns which are shown to form an appreciable part of 

 the diet of this duck, McAtee (1918) says: "Mallards sometimes resort to 

 woods where they can obtain acorns, and occasionally a bird takes so 

 many that it is unable to fly. In connection with acorns it is appropriate 

 to mention hickory nuts, contained in 96 Mallard gizzards. These hard 

 nuts might be thought beyond the powers of a duck to digest, but, on the 

 contrary, they are taken care of with ease, being broken by the great 

 pressure exerted by the gizzard as they are on the point of entering that 

 organ. Once wholly within they quickly are ground to fine fragments." 

 A similar instance is recorded in the "Life Story" of the Wood Duck, 

 which also appears to have no difficulty in disposing of the equally hard 

 nuts of the bitter pecan. 



The Mallard is a great destroyer of mosquito life. The following 

 is condensed from an article which the late Dr. S. G. Dixon, while 

 Health Commissioner of Pennsylvania, published in the Journal of the 

 American Medical Association, in 1914: Two dams were constructed on 

 a stream so that the ponds would present exactly the same conditions. 

 One was stocked with goldfish and in the other 20 Mallards were allowed 

 to feed. After a short time the duck pond was entirely free from mos- 

 quitoes while the fish pond was teeming with young insects in different 

 cycles of life. The well-fed Mallards were then admitted to the infested 



pond, where they soon recog- 

 nized the presence of larvae 

 and pupae of the mosquitoes 

 and immediately turned 

 their attention to these, 

 ravenously devouring them 

 in preference to any other 

 food present. At the end of 

 24 hours no pupae were to 

 be found and in 48 hours 

 only a few of the larvae sur- 

 vived. He adds: "For some 

 years I have been using ducks 

 to keep down mosquitoes in 

 swamps that would have been 

 very expensive to drain, but 

 I never fully appreciated the 

 high degree of efficiency of 

 the duck as a destroyer of 

 mosquito life until the fore- 

 going test was mad e." 

 (Author's Note: There is no 

 doubt that ducks are great 



