Saying Goodbye to Mesker Park Zoo Icon, Berta the Glorious Granny Gibbon

Just look at that beautiful smile. If you visited Mesker Park Zoo & Botanic Garden in the past twenty years, you fell in love with this glorious Gibbon. Berta.

Gibbon or Gremlin?

A Mueller's Grey Gibbon, to be exact. Some folks thought she looked a bit like a critter from the 80s movie, Gremlins, but she would assure you it was perfectly fine to feed her any time of day.

@meskerparkzooaazk4.18.2025 Don't feed her after midnight! Berta might turn into a gremlin!♬ Gremlins (Radio Edit) - E-Force

Beautiful Berta, the Oldest Grey Gibbon

I've always thought she looked more like a Muppet. Judging everyone from the treetops like Statler and Waldorf. At her age, she earned the right. This ole gal LOVED to sunbathe. Berta's biggest fans called her "Grandma Monkey," which makes sense as she was the oldest of her kind known to man at 59 years old. The average age for a Mueller's Grey Gibbon is mid-40s in captivity or mid-20s out in the wild.

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Berta the Grey Gibbon of Mesker Park Zoo Passes Away

Today, officials made a very sad announcement:

In July, Berta celebrated her 59th birthday – an extraordinary milestone. She received a “cake”, special enrichment, and the most adorable Happy Birthday song from our Camp Zoofari kiddos. While the loss of Berta is extremely heartfelt for her keepers, staff, and visitors alike, it is a true testament to the care that the team at Mesker Park Zoo & Botanic Garden provides to our animals. The bond built with Berta spanned beyond just her keepers and animal care team.

To our knowledge, Berta was the oldest known Mueller’s grey gibbon in the United States, living far beyond the typical life expectancy of 25–30 years. Her age was estimated at 59, as her true birthdate is unknown. She arrived at Mesker Park Zoo in 2001 with her partner, Freddy, who passed away in 2015. Together they created their own special duet: every bonded pair of gibbons has a unique song, and while Freddy had his part, in true Berta fashion, she made sure she was the star.

Keeper Rachel, who spent 15 years caring for Berta, shared that one of her favorite things about her was her sass:

“If you gave her a banana or orange (something she normally liked), and she wasn’t in the mood for it, she’d take it and throw it right down in disgust. She never hid her opinions.”

In her final moments, Berta was surrounded by her keepers, the people who loved her deeply, and received some of her favorite snacks.

Her loss is immeasurable, but so is the joy she brought during her 24 years here. To honor her, we invite you to share your favorite photos, stories, and memories of Berta below. And, if you’d like to celebrate her life in a small way, enjoy one of her favorite treats today, a blueberry or a craisin, and think of her.

Berta’s spirit will always echo through Mesker Park Zoo & Botanic Garden, and her legacy will continue on by making contributions to science even after her passing. Due to her age, she will be a unique contributor to a scientific study evaluating ape biomechanics. The information gained in this study will aid in the overall advancement of knowledge and bettering the care of primates globally.

She was sassy. She was strong. She was unforgettable.

Please be patient and kind to staff as we navigate this immense loss of Miss Berta B

Love,

You can read the tributes and share your own on the Facebook post there, or tell us how she was special to you on our app chat. I'll remember Berta every time I eat a blueberry. She will be missed!