- London Zoo is using frozen blood lollies to help lions and tigers stay cool during heatwaves.
- The treats are designed to mimic natural feeding behaviors while encouraging hydration and cooling through slow consumption.
- Zoos are adapting animal care protocols to address rising temperatures due to climate change.
- Large carnivores like lions and tigers are vulnerable to heat stress in temperate climates.
- Monitoring core body temperatures and behavioral cues helps keepers prevent heat-related issues in big cats.
London Zoo is using frozen blood lollies to help lions and tigers stay cool and hydrated during a prolonged heatwave, a strategy that merges animal enrichment with thermoregulation. The treats — made from animal blood, meat, and water — are designed to mimic natural feeding behaviors while encouraging hydration and cooling through slow consumption. This initiative, deployed during a record-breaking UK bank holiday weekend in May 2026, reflects how zoological institutions are adapting animal care protocols to应对 rising temperatures due to climate change, ensuring both physical health and psychological well-being for large carnivores in captivity.
What the Data Shows About Heat Stress in Captive Big Cats
Studies show that large carnivores such as lions (Panthera leo) and tigers (Panthera tigris) are vulnerable to heat stress when ambient temperatures exceed 28°C (82°F), particularly in temperate climates where animals may not be fully acclimatized. According to the Journal of Zoo and Wildlife Medicine, heat stress can lead to reduced activity, decreased appetite, and increased respiratory rates in big cats. At London Zoo, keepers monitor core body temperatures and behavioral cues closely during heat events. During the May 2026 heatwave, when temperatures reached 31°C in London — among the highest recorded for a bank holiday weekend — the use of blood lollies correlated with a 40% increase in observed hydration behaviors and sustained feeding engagement. These frozen treats, which can take up to two hours to consume, also provide sensory stimulation and align with natural scavenging patterns, offering both physiological and psychological benefits.
Key Players: Zoologists, Keepers, and Animal Welfare Scientists
The initiative is led by the animal care team at ZSL London Zoo, part of the Zoological Society of London (ZSL), a conservation organization founded in 1826. Senior carnivore keepers collaborate with veterinary scientists and ethologists to design enrichment strategies that support natural behaviors. Dr. Emily Carter, ZSL’s head of animal welfare, explained in a public briefing that the blood used in the lollies is a byproduct of regulated meat sourcing for other zoo animals, making the practice both sustainable and ethical. The team works with climate adaptation specialists to project seasonal temperature impacts and adjust enclosure environments accordingly. This includes shaded dens, misting systems, and water pools. The blood lollies are just one component of a broader thermal management strategy, reflecting a growing trend in zoos worldwide to adopt evidence-based, climate-responsive care models.
Trade-Offs: Enrichment Benefits vs. Public Perception and Logistics
While the blood lollies offer clear benefits in terms of hydration, cooling, and behavioral engagement, they also present challenges. Public reaction has been mixed, with some visitors expressing discomfort at the idea of feeding blood-based treats, despite their natural relevance to carnivore diets. Zoo educators have had to increase outreach to explain the biological rationale and sourcing ethics. Logistically, the preparation requires strict hygiene controls and freezer capacity, adding operational complexity. However, the cost is relatively low — each lolly costs under £3 to produce — and the effort is offset by reduced veterinary interventions during heat events. The approach also raises broader questions about how zoos balance animal needs with visitor expectations, particularly as climate adaptation tools become more visible and unconventional.
Why This Is Happening Now: Climate Trends and Zoo Innovation
The use of blood ice lollies has gained urgency due to increasingly frequent and intense heatwaves in the UK, a trend linked to climate change. The Met Office recorded 2025 as the warmest year on record for England, and projections suggest summer temperatures could regularly exceed 30°C by 2030. For institutions like London Zoo, which houses species evolved in warmer climates but managed in a traditionally cool region, this shift demands proactive adaptation. While big cats originate from Africa and Asia, where high temperatures are normal, captive animals often lack the freedom to seek optimal microclimates. The lollies are part of a suite of innovations — including UV-adjusted lighting, soil composition changes, and timed feeding — now being standardized across European zoos, signaling a new era of climate-informed animal husbandry.
Where We Go From Here
Over the next 6–12 months, three scenarios could unfold. First, the blood lolly model may be adopted by other UK and northern European zoos as summer temperatures rise, particularly for carnivores and scavengers. Second, public education campaigns could transform the lollies into a symbolic tool for discussing climate adaptation and animal nutrition, potentially even inspiring interactive exhibits. Third, if regulatory or public pressure increases, zoos might develop plant-based or synthetic alternatives that mimic the texture and cooling properties without using animal byproducts. Regardless of the path, the trend points toward more personalized, climate-responsive care across zoological institutions.
Bottom line — London Zoo’s blood ice lollies exemplify how animal welfare innovation is evolving in response to climate change, blending biology, behavior, and practical care to keep big cats healthy, cool, and engaged in a warming world.
Source: The Guardian