At London Zoo, the annual weigh-in has become much more than a routine check—it’s a spectacle that brings together keepers, curious visitors, and a cast of animals ranging from the grand to the minuscule. On August 19, 2025, the tradition continued as animals from across the zoo lined up, ambled over, or were gently coaxed onto scales of all shapes and sizes, all in the name of health and conservation.
According to reports from London Zoo and coverage by Big Country News Connection, this year’s event was a lively affair, with zookeepers and animals both taking center stage. The weigh-in is no small feat: every mammal, bird, reptile, fish, and invertebrate in the zoo is weighed and measured. The process, as the zoo explained, is critical for monitoring each animal’s health, tracking their development, and even identifying pregnancies that might otherwise go unnoticed.
One of the stars of the day was Priscilla, a 30-year-old giant Galapagos tortoise. Getting a creature of her size and temperament onto a scale isn’t always straightforward, but the keepers had a tried-and-true method: lettuce. As Priscilla munched contentedly, she stepped onto a board scale, her participation emblematic of the gentle coaxing and careful planning that goes into the event. As Big Country News Connection described, "Priscilla, a 30-year-old giant Galapagos tortoise, was lured onto a board scale with a lettuce snack, which she can be seen munching on in a sweet video."
But Priscilla wasn’t the only animal drawing attention. A pair of capybaras named Gizmo and Kiwi—recognized as the world’s largest rodents—made their own appearances, hopping onto the scales with the help of zookeeper Poppy Jewell. Penguins, meanwhile, displayed surprising orderliness. The Humboldt penguins, under the care of zookeeper Jessica Ray, were seen waiting patiently in line for their turn—proof that even in the animal kingdom, some creatures are sticklers for protocol.
The weigh-in included a delightful variety of species. Ring-tailed lemurs, guided by Chelsea Reid-Johnson, and magnolia land snails, handled by Cat Dixon, were among the participants. The tiny Darwin’s frogs, weighing in at under two grams and measuring just two centimeters, showed that the event truly spans the full spectrum of the animal world. Even the giant hooded katydid, weighed by Jamie Mitchell, had its moment in the spotlight.
Each animal’s measurements are more than just numbers. As the zoo explained, the data collected is meticulously recorded in the Zoological Information Management System (ZIMS), a global database shared with animal carers and conservationists. This allows experts around the world to compare vital statistics on thousands of endangered species, supporting broader conservation efforts. "The zoo says that their weigh-in is an opportunity to ensure the information recorded for each individual is up-to-date and accurate. Each measurement is added to the Zoological Information Management System (ZIMS), a database shared with animal carers and conservationists all over the world. This helps experts to compare important information on thousands of endangered species," reported Big Country News Connection.
Some animals, like the penguins and tortoises, have been trained to step onto the scales, often with the promise of a favorite snack. Others require a bit more creativity. For the more elusive or nervous residents, keepers employ hidden scales in doorways or other clever tricks to ensure accurate readings without causing stress. It’s a process that requires patience, ingenuity, and a deep understanding of each animal’s personality.
Daniel Simmonds, the zoo’s animal operations manager, highlighted the significance of the weigh-in for animal care and conservation. In his words, "The London Zoo Annual Weigh In is not just about numbers on a scale; regular weigh-ins help zookeepers track the health of our animals—including the capybaras, tortoises, and penguins—and genuinely help us manage the care of these animals, who play a vital role in our global conservation efforts." Simmonds also underscored the importance of diet and enrichment: "Our animals here at London Zoo receive world-class care—and a huge part of this is our meticulous planning of their diets. Our zoo-tritionist ensures every animal is getting the nutrients they need, while our keepers devise ways to feed the animals that spark all of their natural instincts—keeping them fit and challenged."
The annual weigh-in is as much about animal welfare as it is about scientific rigor. By keeping close tabs on weight and growth, zookeepers can spot early signs of health issues, adjust diets, and even detect pregnancies that might otherwise be missed. This proactive approach is especially crucial for endangered species, where every individual counts. The zoo’s commitment to sharing its findings through ZIMS means that the benefits of the weigh-in extend far beyond the gates of Regent’s Park, helping conservationists worldwide make informed decisions about species management.
Visitors to the zoo on weigh-in day are treated to a behind-the-scenes look at the care and attention each animal receives. There’s a certain magic in watching a giant tortoise lumber onto a scale for a snack or seeing a line of penguins waiting their turn. It’s a reminder of the personalities and quirks that make each animal unique, and of the dedication of the staff who care for them.
For the zookeepers, the event is both a logistical challenge and a labor of love. Coordinating the weigh-in for hundreds of animals—some cooperative, others less so—requires teamwork, creativity, and a deep well of patience. But the rewards are clear: healthier animals, better data for conservation, and a chance to engage the public in the ongoing work of protecting wildlife.
As the scales are packed away and the data logged, the keepers at London Zoo can take pride in another successful weigh-in. It’s an annual ritual that blends science, care, and a dash of spectacle—a testament to the vital role zoos play in both animal welfare and global conservation.
With each weigh-in, London Zoo not only safeguards the health of its residents but also contributes to the worldwide effort to understand and protect the planet’s most vulnerable species. And for anyone lucky enough to witness the event, it’s a heartwarming display of curiosity, cooperation, and the enduring bond between humans and animals.
