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July 1, 2011

Celebrating the 30th Anniversary of the Black-Footed Ferret’s Rediscovery - Part VI: Breeding Season

After 72 hours of being together, the black-footed ferret (BFF) female is separated from the male and she is returned to her enclosure.  Four days after separation, she is given her final vaginal flush for the year.  This check is to see if she has been induced to ovulate.  If she has, then her epithelial cells will look as they did at the beginning of her estrus cycle, obvious nuclei and very few cells with orange stain.  If she has not ovulated then they will look as they did before pairing, no nuclei and many orange keratinized cells. The female is re-paired immediately with a male if she has not ovulated and will sometimes be given hormones if she will not ovulate after a few pairings.  Once ovulation occurs, the females are disturbed as little as possible. 
The gestation or pregnancy period for BFFs is 42 days.  The diet is increased every two weeks and is almost doubled by the time she is due.  An infra-red video camera is installed on the nest box and we wait with anticipation for the kits to be born. BFF gestation period is almost like clockwork.  Most of our births occur right on the 42nd day and even near the time when the male and female were put together for breeding.  If we paired them in the morning, then the kits will usually be born in the morning.  If we paired them later in the day, then they will be born later that evening.  Since we have numerous female BFFs, a whelping calendar is created so we can keep track of all the due dates. 

For 2011, 11 SSP females were paired and 4 additional females that were non-releasable but over the age of four.  The additional 4 older females are not included in our primary breeding numbers as they are not as likely to produce kits.   One of our SSP females did not ovulate after 2 breeding attempts so she was given a hormone injection which did cause her to finally ovulate.   The remaining females that were bred and ovulated had no other issues during their gestation periods.
Bunting’s 4 healthy kits on camera while 
she is away getting a drink of water. 
Our first due date was on May 21st and our last was on June 22nd. On May 21st a litter of 6 kits were born!!!  Bunting Studbook #6376 is the dam (mother).  She came to Cheyenne Mountain Zoo in 2009 as a one year old and unfortunately did not produce kits in 2010.  This year, however she proved otherwise.  For reasons unknown, only 4 of the kits visible on the camera were moving.  As we do not want to jeopardize the well being of the entire litter, we generally do not interfere and let the dams take care of the deceased kits as nature would intend. The four remaining kits looked as healthy as ever and now Bunting has a lot of work ahead of her as a new mom.