( 



BREEDING SEASON AND GESTATION PERIOD OF MARTENS 5 



In many females there are two periods of two or three days each 

 •during which they will accept service. These two periods are usually 

 from one to two weeks apart. 



During the oestrual period the female frequently makes a clucking 

 noise entirely different from that made at other times, apparently a 

 call to attract the male. She squats and urinates frequently, espe- 

 cially on stones and other objects in the pens, and climbs and mounts 

 the male when he is apparently passive. Quite often she switches her 

 tail nervously and wrestles with him considerably, though squealing 

 loudly when he treats her too roughly. When she does not accept 

 service readily, the male will chase and struggle with her until 

 mating is accomplished. 



The question has arisen in connection with these experiments with 

 martens whether the fertilized ovum may lie in a dormant state for 

 several months before noticeable embryonic development begins, as 

 in the roe deer. Williams 3 in discussing the duration of pregnancy 

 in wild animals, states : 



Harms notes the peculiar fact that in the deer there Is a period of 40 weeks 

 between fertilization and the birth of the young, but that this time does not 

 represent" the period of development of the fetus as we understand it in most 

 animals. The ovum of the deer undergoes segmentation and then lies in the 

 uterus for 4 months in an essentially dormant state. About December the dis- 

 tinctive embryonic development begins, and birth follows in May or June — 

 about 5 months later. * * * It is suggested that this delay in the develop- 

 ment of the young is a provision by which it may be born at a favorable season 

 of the year. 



Apparently the same condition obtains with martens, as females 

 trapped and killed in the wild have not shown macroscopic signs of 

 pregnancy until late in winter. 



RESEARCH IN OTHER COUNTRIES 



Heinrich Prell, of Munchen, Germany, after a visit to the United 

 States during the winter of 1927 for the purpose of studying fur- 

 farming developments, wrote the Biological Survey as follows : 



One of our German breeders on my advice has kept together a pair of stone 

 martens. On July 16 he observed a mating at about r J o'clock in the morning 

 and again about 5 in the evening. A forester observed a pair of martens 

 mating at about. 4 o'clock in the morning. These two observations may prove 

 that the European marten [Martcs foina] has the same biology as the American 

 marten. 



On advice from Doctor Prell. H. Reinhardt conducted experiments 

 with stone martens. He observed matings on July 16, 1927, July 

 5, 6, and 7, 1928, and on June 28. 1929. The first young were born on 

 April 7. 1929. The information contained in Doctor Reinhardt's 

 article 4 is almost identical with our observations in the United 

 States. 



V. Generosoff, of Leningrad, Russia, in a letter to the Biological 

 Survey states : 



Tonr discovery of the breeding period of American martens leads me to 

 believe that the same is true of our sables [Martes zibeUma,] * * *. This 



Williams, W. L. veterinary obstetrics, p. 1G0. Ithaca, N. Y. 1917. 



* TEINHAMjT, H. BEITRAG ZUR Zl'CHT UNO JUGENDENTWICKLUNG DES STEIN'MARDERS. 



Deutsche rviztierzuchter .No. 15 : 445-^148. Munchen. 1929. 



