The investigations were carried out in 2006 and 2007 in a mink farm in West Pomerania. In the 1st year 1225 standard mink and 2110 wild mink were included. The results showed that embryo implantations occurred in the time from March 19 to April 29. In 2006 was the implantation time in both colors almost the same (March 20 to April 20 in standard mink and March 20 to April 19 in the wild mink). A comparison of implantation time of embryos within the wild mink in both years 2006 and 2007 showed that this time in 2007 was clearly longer than in previous year (March 19 to April 29). In 2006 the pregnancy duration in wild females mated earlier was significantly longer. About 90 percent of wild mink mated between March 8 and 15 showed a pregnancy duration 48 to 61 days, whereas in mink mated between March 26–27 94 percent of pregnancies lasted only 34–47 days; similarly was the pregnancy duration in 2007. Clearly shorter gestation length was noted in females mated after March 10, since in about 90 percent of cases the shorter pregnancy duration (34–47 days) was observed in mink mated between March 23–24. A significantly (p < 0.05) negative correlation was found between the date of first mating and pregnancy duration in both colors (r = –0.562 to –0.676).

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