66 Department of Conservation of Louisiana 



fur animal supply with our part of the continent, still it is 

 important to point out that there have been what appear to 

 be periodic fluctuations in the muskrat population not 

 wholly attributable to trapping. A matter so important 

 warrants a great deal of local research as to causes, and 

 if depletion by epidemics rather than by trapping is the 

 factor in the periodic and extreme fluctuations in our musk- 

 rat crop in the past few years, the causes should be sought 

 out and remedial efforts expended to prevent reoccurrence 

 if it is possible. 



California's Plague of Mice 



In January, 1927, scientists and many others interested 

 in rodent reproduction, followed newspaper and other re- 

 ports of an unprecedented outbreak of mice in the Buena 

 Vista Lake section of southern California. According to 

 some of the stories, "millions upon millions" of the animals 

 swarmed on the highways, and one oil company was cred- 

 ited with killing "four tons of mice." 



The outbreak, naturally, was immediately investigated 

 by the California Fish and Game Commission and by the 

 Museum of Vertebrate Zoology of the University of Cali- 

 fornia, Director Joseph Grinnell delegating E. Raymond 

 Hall, curator of mammology, to make the study. Mr. Hall 

 estimated that the affected area was about eighteen miles 

 in diameter, that the rodent outbreak was by the common 

 house mouse (Mus Musculus) , and he found as many as 

 seventeen mice per square yard over an area of many acres 

 planted in kafir corn. Computed from the counts made on 

 the measured areas, Mr. Hall arrived at the startling num- 

 ber of 82,280 mice per acre, or 2,468 pounds of mice per 

 acre, doing damage and migrating to other parts. 



A very interesting and valuable account of this plague 

 was written by Mr. Hall and published by the University 

 of California, 15 and the liberty is taken of quoting from 

 the bulletin wherein it bears on the problem of periodic 

 fluctuations of rodents. 



' Hall, E. Raymond, An Outbreak of House Mice, pp. 189-203, University 

 of California, 1927. 



