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Scientists artificially inseminate Mexican wolf to help endangered population rebound

Ese Olumhense, Chicago Tribune on

Published in News & Features

CHICAGO -- The scene mirrors one popular in most medical television dramas: A sedated patient lies on a table as practitioners, their hands gloved, bustle about handling tubes and tongs, vials and syringes. Computer monitors, flickering with real-time vital information, hum in the background of beeping machines, walkie-talkie static and urgent voices.

And though the procedure being done this day, artificial insemination, is fairly typical, the patient, Zana, a Mexican wolf living at the Brookfield Zoo, is anything but.

For the first time in the state, scientists from the Chicago Zoological Society and a team assembled by the Reproductive and Behavioral Sciences Department at the St. Louis Zoo used artificial insemination in an effort to improve the genetic diversity of the Mexican wolf population, which has been endangered since 1976. At that time, only seven of these wolves were left in the wild, experts said.

Decades later, and more than 1,000 miles away from the species' original habitat in the Southwestern U.S. and Mexico, scientists at Brookfield are deploying new reproductive tools and technologies to advance the recovery of the Mexican wolf. Artificial insemination is among the latest of these. Scientists say it holds promise for the Mexican wolf -- which now has a population of over 280 in 55 zoos and other institutions and an estimated 150 living in the wild -- as well as other species at the fringes of extinction.

The recent procedure, which used a frozen semen sample from Redford, a Mexican wolf living in Arizona, is "pretty revolutionary," said Joan Daniels, curator of mammals at the zoological society, which manages Brookfield.

Frozen samples, collected in a medical setting, are easier to transport than actual animals, veterinary and reproductive physiology experts point out. That was previously the practice for many breeding programs, in which animals were paired with the hope they would produce offspring. That method, both time- and resource-intensive, was not always certain to work, either.

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"Many (animals) are really fussy," said Cheryl Asa, a reproductive physiologist and former director of research at the St. Louis Zoo. Some animals rebuff proposed partners, she said, even after a year or two of expert-engineered courtship.

"Using artificial insemination completely gets around that," Asa said. "It's so much easier if you can ship a semen sample."

The decision to use Redford's sample, collected in 2014 when he lived at Brookfield, was deliberate. The pairing was orchestrated using complex computer software to ward off a "genetic bottleneck," which happens when there are limited animals for breeding. That situation decreases the genetic diversity of the overall wolf population and weakens the species, experts said.

Because many of Brookfield's wolves are already related, Zana, the pack's alpha female, and the other two female wolves are kept separately from the seven males during winter, when the females experience their once-yearly ovulation. (Female wolves, like their human counterparts, also have hormonal contraceptive options that include a pill and an implant, though these can have worrisome side effects, Daniels said.)


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