News Release

Contact: Sondra Katzen, Public Relations, (708) 688-8351,
May 16, 2017
NOTE: Images of the Mexican gray wolf puppies may be downloaded below.

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Mexican Gray Wolves Born at Brookfield Zoo Venture Out of Den

Brookfield, Ill. – The five nearly 4-week-old Mexican gray wolf puppies at Brookfield Zoo emerged from their den at the Regenstein Wolf Woods habitat this past weekend. Three of the pups—all males—were born at the zoo on April 22. The remaining two pups—a male and a female—were born to the San Mateo wild wolf pack in New Mexico and placed in the zoo’s pack for cross-fostering.

The Chicago Zoological Society (CZS), which manages Brookfield Zoo, is a partner in the U.S. Fish and Wildlife Service’s Mexican Gray Wolf Recovery Program. To enhance the genetic diversity of the wild population and that of Mexican gray wolves in breeding and care facilities, USFWS recommended that two pups from Brookfield Zoo’s litter and two wild-born puppies be cross-fostered. In early May, this was accomplished when CZS animal care staff traveled to New Mexico with two puppies from the zoo’s litter to be placed in the wild pack and then returned to Illinois with two puppies from the wild pack. The cross-fostering was a success. Zana, the alpha female at Brookfield Zoo, has been seen caring for the litter, and although USFWS biologists do not have full visual access to the San Mateo litter, they report the adult pair has continued to stay in the area of the wild den site likely caring for the puppies.

A wolf pack usually consists of an alpha male and female (the breeding pair), yearlings from the previous year’s litter, and new pups. This is precisely the structure of the 10-member pack at Brookfield Zoo: 5-year-old Zana and her 7-year-old mate Flint, three of their offspring born in 2016, and the puppies. The species has bonding and caregiving behaviors in a social structure that is second only to those of humans and primates in complexity. Pack members use an array of vocalizations to communicate, including howls, yips, squeals, growls, and barks. Guests visiting the zoo may witness pack members displaying a variety of facial expressions and body postures that also play an important role in communication. These displays may signify dominance or submission, play, and greeting ceremonies with lots of licking. Additionally, once the pups are weaned between six and eight weeks, they will whine, nudge, nibble, or lick the face and corners of an adult’s mouth to encourage it to regurgitate food for them.

Mexican gray wolves are the rarest subspecies of gray wolves in North America. Approximately 4,000 wolves once lived in their historic range, which included central and northern Mexico and the southwestern United States. In May 1976, USFWS added the species to the Endangered Species List. From the 1980s until 1998, when reintroduction efforts began, Mexican gray wolves were considered extinct in the wild. Their demise, which began in the early 1900s, was the result of antipredator campaigns in the United States and Mexico.

As of August 2016, the population of the species in professional care is 245 individuals in 53 institutions. A minimum of 113 Mexican gray wolves live in the wild in the United States and approximately 20 live in Mexico.

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About the Chicago Zoological Society
The mission of the Chicago Zoological Society is to inspire conservation leadership by connecting people with wildlife and nature. The Chicago Zoological Society is a private nonprofit organization that operates Brookfield Zoo on land owned by the Forest Preserves of Cook County. The Society is known throughout the world for its international role in animal population management and wildlife conservation. Its Center for the Science of Animal Care and Welfare is at the forefront of animal care that strives to discover and implement innovative approaches to zoo animal management. Brookfield Zoo is the first zoo in the world to be awarded the Humane Certified™ certification mark for the care and welfare of its animals, meeting American Humane Association’s rigorous certification standards. Open every day of the year, the zoo is located at 8400 31st Street in Brookfield, Illinois, between the Stevenson (I-55) and Eisenhower (I-290) expressways and is also accessible via the Tri-State Tollway (I-294), Metra commuter line, CTA and PACE bus service. For further information, visit


Sondra Katzen
Media Relations Manager
Office: 708-688-8351
Cell Phone: 708-903-2071


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