Oakland Zoo’s Last Cubs of the Remaining Mountain Lion Rescue Trio, Fern and Thistle, Head to New Home at the Phoenix Zoo

Oakland, CA May 28, 2025… Oakland Zoo is excited to announce that mountain lion cubs, Fern (female) and Thistle (male), of the trio of cubs, rescued back in January of this year, have made their way to their new home at the Phoenix Zoo in Phoenix, Arizona, another Associations of Zoos and Aquariums (AZA) accredited institution. The cubs received wellness exams before their departure, and Fern underwent a laparoscopic spay, a minimally invasive procedure, while Thistle was neutered. Both have recovered well after their surgeries and were ready to head out to Phoenix this past Monday. Over the past few months, the animal care staff at Oakland Zoo have used voluntary positive reinforcement training with Fern and Thistle to help them become comfortable traveling and receiving their vaccines before heading to the Phoenix Zoo. Fern and Thistle moved had no trouble shifting into their crates for their journey to their new home.  

“We are honored to have cared for these cubs and to have helped find new forever homes for them at two AZA accredited institutions. Thanks to the Portola Valley and Oakland Zoo communities, we have received tremendous support that has allowed us to expand awareness about the importance of coexistence with wildlife. By raising awareness, we hope to reduce the need for future rescues and create a world where people and wildlife thrive together” says Nik Dehejia, CEO of Oakland Zoo.  

Upon arrival at the Phoenix Zoo, the pair of cubs are spending time acclimating in the night house to become accustomed to their surroundings as well as their keepers. Phoenix Zoo Animal Care staff describe the cubs as curious about their new surroundings, very alert, and in great shape after their move. Thistle was a bit more courageous and immediately came out of his crate to eat, while Fern was more cautious and took her time getting to know her new Zoo family.

Once the cubs are comfortable, the Zoo will begin offering access to their expansive brand-new habitat, Big Cats of Arizona, which opened the first week of April. This stunning new habitat is part of the Arizona Trail, an area of the Zoo dedicated to showcasing species native to the state and celebrating the rich biodiversity of the Sonoran Desert. Housing the cubs at the Phoenix Zoo not only provides a naturalistic and enriching environment tailored to their needs but also helps highlight the importance of local conservation efforts and the vital role native species play in Arizona’s ecosystems. For now, they will remain in their nighthouse as they adjust to their new surroundings and get to know their new Animal Care team at Phoenix Zoo.

“The Phoenix Zoo is committed to providing Fern and Thistle with compassionate care and the support they need to thrive,” says Bert Castro, President and CEO of the Phoenix Zoo. “Our friends at Oakland Zoo have done a tremendous job providing the cubs with a safe and nurturing start after the loss of their mother, and we are honored to continue that journey here in Arizona.”

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Mountain lions are masters of adaptation, moving seamlessly between deserts, forests, and foothills. They have the largest geographic range of any land mammal. However, their habitats are increasingly fragmented as human expansion encroaches on mountain lion territory, causing vital movement corridors to be blocked by highways and buildings. Mountain lions require large territories to thrive, so addressing compromised ecosystems is essential for their survival. Like many other wild animals, mountain lions also face increasing threats to their habitat, as well as injury and death due to wildfires.  

The Phoenix Zoo and Oakland Zoo are committed to enhancing connectivity, fostering coexistence, and advocating for wildlife in all environments. To coexist with pumas and other wildlife, small changes can have a significant impact, such as driving slowly in areas where wildlife cross roadways to prevent car strikes as they navigate their ecosystems. Coexistence is vital for the survival of this species and helps maintain the rich biodiversity of California, Arizona, and beyond.  

For more information about the rescued cubs' backgrounds, Oakland Zoo’s Mountain Lion Rescue Program, and the Phoenix Zoo, please refer to the FAQ list below:

Where were Fern and Thistle found? What happened to their mother?

Fern (female), Thistle (male), and Spruce (male) were found in Portola Valley, San Mateo County. California Department of Fish and Wildlife (CDFW) believes the mother of these three cubs was the same female lion hit by a car on Portola Valley Road about 0.3 miles from where Fern, Thistle, and Spruce were found. While there were many witnesses of the mountain lion after it was hit, the carcass has since disappeared and is still being investigated.

Why can’t the cubs be released to the wild?

In the wild, mountain lion cubs need about two years with their mother to learn survival skills. Because Fern, Thistle, and Spruce are so young, they lacked those skills and could not be returned to the wild.

How are new homes for mountain lions rescued by Oakland Zoo chosen? Where is their brother Spruce now?

CDFW selects locations with the animals' welfare and wellbeing in mind. The Zoo cares for the cubs and then assists CDFW with transporting them to appropriate institutions. In early April, Spruce moved to Birmingham Zoo where he met his new companion, Juniper, which he was paired with based on their based on their similar personalities and age.

Why couldn’t the cub trio be introduced to Oakland Zoo’s resident mountain lions?

Many factors are considered when introducing animals – personalities, age, AZA’s Species Survival Plan recommendations, etc.– and all decisions are made with the animal’s welfare and wellbeing in mind. The trio was determined not to be the perfect match for Oakland Zoo’s resident mountain lions and Briar, another rescued puma the Zoo is caring for.

How is the separation of Fern and Thistle from their brother like what this species experiences in the wild?

In the wild, mountain lion kittens typically remain with their mother for 18 to 24 months, during which they learn essential survival skills before dispersing to establish their territories. The trio's separation aligns with what this species would normally experience in the wild.

What is Fern and Thistle’s habitat like at the Phoenix Zoo?

The habitat Fern and Thistle will be housed in is the newest addition to the Phoenix Zoo’s Arizona Trail, called Big Cats of Arizona. Fern and Thistle have approximately 2,500 square feet of habitat space with climbing structures, ample shaded areas, state-of-the-art cooling systems, and a variety of enrichment elements designed to encourage exploration of the habitat. Neighbors to Fern and Thistle are two jaguars; Caipora and Saban.

How much does it cost Oakland Zoo to care for mountain lion cubs?

Cubs come to Oakland Zoo with various needs and symptoms; some stay only a matter of weeks, others many months. On average, mountain lion cubs spend 8.5 days in the Intensive Care Unit, which requires constant staff care. The average cub costs roughly $18,000 monthly in veterinary and animal care. These efforts are supported by donations from the community.

How can you help support Oakland Zoo and its Mountain Lion Rescue program?

Oakland Zoo relies on philanthropic support from the community to fund our conservation programs, including the Mountain Lion Rescue program.

You can make a donation to Oakland Zoo online at www.oaklandzoo.org/support or learn about other ways to give on our website at www.oaklandzoo.org/donate.

Questions can be directed to the Development team at impact@oaklandzoo.org.

What does the Phoenix Zoo do to support mountain lion conservation?

The Phoenix Zoo uses wildlife cameras in the Atascosa Complex to study an important corridor for many native Arizona species, including mountain lions. The Zoo has recorded some amazing videos of healthy mountain lions roaming throughout the study area, including lionesses raising cubs. The Zoo is sharing their findings from this project with others working to protect wildlife and habitats in the region. To help continue this work you can donate at www.phoenixzoo.org/support.

The Phoenix Zoo is building a specialized quarantine and holding facility, the Doornbos Animal Rescue & Care Center. This $5.5-million-dollar project will play a crucial role in the care of animals rescued from illegal pet trade, animals arriving from other accredited facilities and those injured and orphaned in the wild, much like Fern and Thistle. To donate to this project, please visit https://www.phoenixzoo.org/holding/

ABOUT OAKLAND ZOO AND THE CONSERVATION SOCIETY OF CALIFORNIA:

Oakland Zoo envisions a flourishing planet where people and wildlife thrive together. The Zoo’s mission is to deepen connections with animals, save wildlife, and inspire champions for the natural world. Oakland Zoo is an accredited Association of Zoos & Aquariums member, managed by the Conservation Society of California, a non-profit organization. ‍

About the Arizona Center for Nature Conservation

The Arizona Center for Nature Conservation operates the Phoenix Zoo. The ACNC advances the stewardship and conservation of animals and their habitats while providing experiences that inspire people and motivate them to care for the natural world.

The Phoenix Zoo is the only zoo in the Valley accredited by the Association of Zoos and Aquariums and is a non-profit zoological park, serving 1.4 million guests annually. The Zoo is home to more than 3,000 animals, many of which are endangered and threatened species. For information on upcoming events, exhibits and activities at the Phoenix Zoo, visit www.phoenixzoo.org.

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