PLEISTOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 503 



In a paper entitled "Das allmahliche Aussterben des Wisents {Bison 

 botiasus, Linn.) im Forste von Bjelowjesha," ^ Mr. Eugen Biichner gives a 

 detailed history of the bison herd in the Bielovicjsha (or Bialowitza) forest, 

 Province of Grodno, in Lithuania, Russia, during the present century. 

 "A careful study of the breeding habits of the bison in the Bieloviejsha 

 forest and elsewhere leaves no room for doubt that the present slow rate of 

 reproduction is an abnormal condition, and that to it is due the rapid 

 approach of the extinction which is the certain fate of the herd under con- 

 sideration. This diminished fertility the author regards as a stigma of 

 degeneration caused by mbreeding. . . . Another indication of the degen- 

 erate condition of the Bieloviejsha herd is seen in the great excess of bulls, 

 which probably outnumber the cows two to one. This is doubtless a result 

 of inbreeding, for Busing ^ has shown that close inbreeding, like a reduced 

 condition of nutrition, is favorable to the production of an excess of males. 

 ... In conclusion, the author considers that his studies of the history of 

 the Bieloviejsha bison leave scarcely room for doubt that inbreeding is 

 the cause of the final extinction of most large mammals. Inbreeding must 

 begin and lead gradually but certainly to the extinction of a species when it, 

 through any cause, has become so reduced in numbers as to be separated 

 into isolated colonies." 



Influence of cold during the reproduction period. — Exceptional cold waves 

 or unusually prolonged cold seasons may cause a temporary loss of food 

 supply or cause the death of the young, which in northern latitudes are 

 usually born in spring. The diminution or loss of young from this cause 

 might act as the first of a series of destructive effects of a progressive secular 

 change. These may be summarized as follows from the actual observa- 

 tions ^ of zoologists upon the Cervidae: (a) disturbed conditions during 

 the conjugation (pairing, mating, rutting) period; (6) enfeebled (through 

 hunger) condition of females during parturition period; (c) severe weather 

 conditions, ice storms, crusted snow, prolonged wet and sleet at time of 

 birth; (d) bulls unable to protect herds; (e) cows unable to protect young 

 from Carnivora through starved condition, or abandoning them when 

 attacked by wolves; (/) enfeebled and miprotected condition of quad- 

 rupeds favorable to increased food supply and consequent multiplication of 

 cursorial and other Carnivora, especially Canidse and Felidae. 



These zoological observations are to a certain extent borne out in palae- 

 ontology by Leith Adams' (" British Fossil Elephants," 1879, Ft. 2, p. 98) 

 observations of the exceptionally large num])er of milk teeth of elephants 

 found in certain Pleistocene deposits, which appears to indicate a high 

 mortality of the young. (See also Holland, p. 471.) 



' Biichner, Eugen, Mem. Acad. Imper. Set. St. Petersbourg, Vol. Ill, no. 2, 1895, pp. 1-30. 

 - Diising, Jen. Zeitschr. Naturwiiss., Vol. XVII, 1884, p. 827. 



^ Communicated by Mr. Madison Grant, Secretary of the Zoological Society of New 

 York. 



