u .1:^ u 



Shillinger and the others studying this prohlem don*t know. But they have 

 a theory. They see at least part of $cii explanation for wild life cycles in 

 some facts v/e've long noted ahout domestic livestock. If you jam a lot of cat- 

 tle together in a pen — and disease breaks out among the cattle— the outhrealr is 

 likely to oe much worse than if you had the some number of cattle scattered out 

 over a big range. Likewise, if you have 300 cottontails on a square mile of 

 land, cji outbreak of talo.remia is likely to be much worse than if you had only 

 a hundred rabbits on the same land. The denser the wild-life population, the 

 more extensive the loss from disease. 



Applying that theory to the cycles of rabbit and grouse population we 

 might explain the cycles something like this: Ever since that low point back in 

 1926, the rabbit and grouse population of the northern woods has been gradually 

 increasing. This year, rabbits, in parti calar, are numerous. If the disease 

 men's theory of cycles is correct, we may find disease running riot for the 

 next year or so and game in the north country of the midwest dying off like flies. 

 In a few years the rabbit and grouse population may again be at a low point. 

 The disease may die down like a forest fire after it gets out of a dense woods 

 into a field of scattered brush. The disease may smolder along for several years 

 until the woods are again full of wild-life. Then, we may see another disea.se 

 epizootic —and another falling off in the supply of game, And so one cycle 

 may follow another. 



But, if those wild-life cycles are all a part of Nature's course, whj'- 

 should we v;orry about them? Why should we try to find out how nxich disease has 

 to do with those cycles, and how disease spreads, and how v;e can control disease? 

 Principally, because a knowledge of wild-life diseases plays an importrnt part 

 in the work of our State and Federal game officials. 



AOrOUITCSI'.mTT! And that's today's story from Uncle Sam's Naturalists about the wile 

 life- cycles and depressions in Nature. We will bring you another storj^- of the 

 Great Out-of~Doors from the United States Biological Survey at this sajae time 

 two weeks from today. 



