128 Game Survey of the North Central States 



Dispersion may possibly represent an impulse, born of deficiency, to seek 

 missing food substances. 



In short, the Halpin hypothesis appears to fit all the observed facts. This 

 of course does not prove the hypothesis. It merely proves the need for controlled 

 experiments to find out what these assumed nutritional deficiencies are, and how 

 to correct them. Professor Halpin thinks that the key to the pheasant riddle, 

 when once found, may prove to be very simple. 



It may at this point well be asked: Is it probable that the pheasants which 

 fail have nutritional requirements radically different from the quail which are 

 closely related to them, and which obviously thrive on the foods which the zone 

 of failure provides? 



Knowledge is insufficient to say that such a difference is probable, but 

 sufficient to say that it is possible. Professor Halpin says Plymouth Rock chickens, 

 for instance, are more susceptible to the bone malformations caused by incorrect 

 rations than are leghorn chickens. It is also possible to say that nutritional re- 

 quirements do not necessarily follow taxonomic relationships. Thus hogs are 

 said to resemble chickens in their needs for special food substances more than 

 they resemble cattle. 



Need of Experimentation. If the foregoing logic is found, in the 

 opinion of competent scientists, to hold water, then the following experiments 

 are needed: 



(1) Locate some southern pheasant stock, either wild or captive, which has 

 not been replenished by northern blood or northern foods for a long time. 



(2) If this cannot be found, "build" some stock of this character. 



(3) See if this unreplenished southern stock will breed on southern foods. 

 Follow its weight and vigor in comparison with northern stock fed on identical 

 foods and kept under identical surroundings. 



(4) If a difference is found, begin to experiment on various foods to locate 

 its source or cause. 



(5) When the source is isolated, it may prove possible to artificially supply 

 the southern ranges with that they lack. Conversely, it may prove possible to 

 increase vigor on northern ranges by augmenting the natural supply of the critical 

 food substances. 



Scientific and Practical Significance. If it should prove to be true 

 that the artificial distribution of these two species is limited by some vitamin, 

 mineral, or other qualitative factor of nutrition, then it follows that the natural 

 range of other species may likewise be determined by similar factors. The sharp 

 and arbitrary nature of species ranges, and their changes or stability in point of 

 time, has long been a puzzle, especially in birds. Some of the western quails, for 

 instance, have range boundaries which appear absolutely arbitrary. 



It also follows that if the identity of the "cause" can be discovered, success- 

 ful controls may become possible. It is thinkable that a mineral, for instance, 

 could be artificially added to the zone of failure. It is even more probable that 



