Productivity and Populations 323 



isms. It is probably not the result of any unknown agents but it is 

 brought about by little understood biological mechanics of well- 

 recognized factors. To say that there is much still to learn about this 

 subject is to state the obvious. 



REFERENCES AND CITATION SOURCES ON PRODUCTIVITY 

 OF THE RUFFED GROUSE, AND ON CYCLES 



Abbot, C. G. Solar Radiation and V^^eather Studies, Smithsonian Misc. Ck)ll., 



Vol. 94, No. 10, Aug. 15, 1935. 

 Allee, W. C. Animal Population Cycles, Scientific Monthly, Vol. 56, No. 6, 



June, 1943. 

 Allen, A. A. Diseases of the Ruffed Grouse, Am. Game, March, 1928. 

 Allen, A. A. Sex Rhythm in the Ruffed Grouse and Other Birds, Auk, Vol. 



LI, No. 2, April, 1934. 

 Anon. Grouse Cycle is Reached in 1933, mimeo. News Release, Wise. Cons. 



Dept., Oct. 18, 1933. 

 Audubon, J. J. The Birds of America, 1856. 

 Baird, S. F., Brewer, T. M., and Ridgeway, R. liistory of North American 



Birds, Vol. Ill, 1905. 

 Braestrup, F. W. The Periodic Die-off in Certain Herbivorous Mammals and 



Birds, Science (New Series), Vol. 92, 2390, Oct. 18, 1940. 

 Bump, Gardiner. The New York Grouse Investigation, Proc. New England 



Game Conference, 1933. 

 Bump, Gardiner. Some Characteristics of the Periodic Fluctuations in Abun- 

 dance of Ruffed Grouse, Trans. 4th, N. A. Wildhfe Conference, 1939. 

 Chapman, F. B. The Development and Utilization of the Wildlife Resources 



of Unglaciated Ohio, Release No. 110, Ohio Wildlife Res. Sta., May 1, 1939. 

 Chitty, Dennis, and Chitty, Helen. Summary of "Canadian Arctic Wildlife 



Enquiry, 1939-40" Journal Animal Ecology, 10 (2), Nov., 1941. 

 Clarke, C. H. D. Fluctuations in Numbers of Ruffed Grouse, Univ. of Toronto 



Studies, No. 41, 1936. 

 Clayton, Henry H. Solar Relations to Weather, 1943. 

 Griddle, Norman. Some Natural Factors Governing the Fluctuations of Grouse 



in Manitoba, Canadian Field-Naturahst, April, 1930. 

 Cross, E. C. Periodic Fluctuations in Numbers of the Red Fox in Ontario, 



Joum. Mammalogy, Vol. 21, pp. 294-306, 1940. 

 Davie, O. Nests and Eggs of North American Birds, 1898. 

 DeLury, R. E. Sunspots and Living Things, Trans. 17th Am. Game Conf., 



1930. 

 DeLury, R. E., and O'Connor, J. L. Regional Types of Response of Wildlife 



to the Sunspot Cycle, Trans. 1st N. A. Wildlffe Conf., 1936. 

 Dillin, J. G. The Effect of Forest Fires on Grouse, Bull. Am. Game Prot. 

 Ass'n, Vol. 9, No. 3, 1920. 



