News Release
Contact: Sondra Katzen, Public Relations, 708.688.8351,
December 10, 2021
 NOTE: Scroll down to end of press release to download photos.

Chicago Zoological Society Staff Saddened by Loss of Mexican Wolf at Brookfield Zoo

Brookfield, Ill. — The Chicago Zoological Society, in consultation with the U.S. Fish and Wildlife Service’s (USFWS) Mexican Wolf Recovery Program and the Association of Zoos and Aquariums’ (AZA) Mexican Wolf Species Survival Plan, made the difficult decision this week to humanely euthanize Sibi (pronounced see-bee), a 9-year-old female Mexican wolf at Brookfield Zoo. Veterinary examinations and a CT scan showed significant deterioration of a front leg joint that could not be repaired surgically or managed with pain relievers.
Sibi was born in managed care in Mexico in 2012. She was eventually transferred to the Endangered Wolf Center (EWC) in Missouri from Mexico, where staff noticed she was limping. An exam revealed foreign particles in her wrist and several areas of her body. The particles turned out to be buckshot, which could not be safely removed. It was apparent that Sibi had been shot prior to her arrival at the EWC.
“It is upsetting to think of an endangered wolf being illegally shot inside what was a protected area in Mexico, but this is the harsh reality wild wolves live with every day. Sibi did very well for most of her life, but it was apparent she was in discomfort recently and her ability to walk normally was declining,” said Joan Daniels, curator for mammals for CZS, which manages Brookfield Zoo.
Sibi produced four litters—two at the EWC and two at the USFWS’s Sevilleta facility in New Mexico. “She was a true ambassador of the hardships that Mexican wolves face in the wild. Her survival and perseverance as an attentive and caring mother were inspiring,” said Daniels.
With the loss of Sibi, the AZA’s Mexican Wolf Species Survival Plan has recommended allowing Vivilette, a 2-year-old female Mexican wolf at Brookfield Zoo, to breed with an 8-year-old named Amigo in 2022. Vivilette was born in managed care in Sevilleta, New Mexico. As a puppy, she was found injured with an open fracture on her right front leg that could not be repaired with surgery. The cause of the injury is unknown, but young wolves often jump and play hard and front leg injuries are not uncommon for both wolves and dogs. Domestic dogs and wolves with missing front limbs learn to compensate and are able to adapt well to walking, running and raising young. USFWS has documented many three-legged wolves raising off-spring and successfully hunting in the wild.
Amigo, who was born at the New York Wolf Center, is an experienced sire having successfully raised two litters at the EWC.

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Photo Captions (credit: Jim Schulz/CZS-Brookfield Zoo)
1425, 8127, and 8757: Sibi, a 9-year-old Mexican wolf at Brookfield Zoo, was humanely euthanized this week after a CT scan showed significant deterioration of a front leg joint that could not be repaired surgically or managed with pain relievers.

About the Chicago Zoological Society
The mission of the Chicago Zoological Society is to inspire conservation leadership by engaging people and communities 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. The zoo is located at 8400 31st Street in Brookfield, Illinois, between the Stevenson (I-55) and Eisenhower (I-290) expressways and also is accessible via the Tri-State Tollway (I-294), Metra commuter line, and 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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