Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=214818
Story Retrieval Date: 5/23/2013 11:20:00 AM CST
Bright white lights filled the examination room at the Brookfield Zoo’s animal hospital. A veterinarian and two veterinary technicians wearing sterile plastic gloves leaned over a metal examination table examining little ball after little ball of fur.
“So… this looks like a little boy,” said veterinarian Jackie Zdziarski-West, as she gave the first of four 8-week-old dwarf mongoose pups his first physical examination.
The following three declarations of sex were the same; the pups were all identified last week as males.
In fact, since September, dwarf mongoose mom, 3-year-old Tavi, has given birth to seven males and zero females.
Christine McKnight, the coordinator of the Association of Zoos and Aquariums’ national Dwarf Mongoose Species Survival Plan, said that there does not appear to be a sex ratio bias when looking at population data.
In other words, it does not appear to be an entirely odd phenomenon that Tavi gave birth to all males two litters in a row.
“Which gender is more valuable to the population depends on the current demographics,” said McKnight, of the Minnesota Zoo in Apple Valley, Minn. “Age structure and sex ratio are both factors in the sustainability of populations. If there is a disruption in the proportion of males to females the overall reproductive success of the population could be affected.”
As far as importance of sex ratios with a pack, said McKnight, lower-ranked mongooses of both genders help take care of the offspring. "You couldn’t surmise one gender was more important to the pack socially,” she said.
Mom, Tavi, is 3 years old and she sired both of her recent litters with 13-year-old Gimbi. But Tavi doesn’t take care of her pups, except to nurse them, and neither does Gimbi.
Instead, the pleasure of taking care of not one, but both current litters of dwarf mongoose males, falls to 9-year-old “uncle” Eugene. He is not genetically related to the pups, however, he is subordinate to Gimbi in the pack.
The sex ratio in the overall North American accredited zoo dwarf mongoose population is about even between males and females, said Joan Daniels, associate curator of mammals at the Brookfield Zoo.