Saving Species Through Food: Lessons from Nature’s Nutrition
- Date: 10 April 2025
- Author: Ellen S. Dierenfeld, Ph.D.
Throughout my career, I’ve had the extraordinary privilege of literally saving species—through food. As a specialist in comparative animal nutrition, I’ve spent decades working at the intersection of wildlife biology and food systems. The principles I’ve learned in conservation nutrition are now informing global efforts to make animal agriculture more sustainable. Whether saving endangered ferrets or feeding livestock with less environmental impact, the core message remains: nutrition matters, from the ground up.
A Ferret, a Falcon, and a Lesson in Whole Prey
One of my earliest and most memorable roles was at the Wildlife Conservation Society, based at New York’s Bronx Zoo. Just months into the job, the last 18 known black-footed ferrets were brought into captivity to kick off an emergency conservation breeding program. These ferrets naturally feast almost entirely on prairie dogs—skin, organs, fat, and all. But in captivity, they were fed skinned and dressed carcasses from the freezer, stripping away essential nutrients.
By consulting with feed manufacturers—and even my great uncle, a retired mink rancher—we designed a diet that mimicked the nutritional profile of wild prey. We also conducted detailed research on the nutrient composition of prairie dogs across life stages, seasons, and locations. That work continues to inform how we feed not just black-footed ferrets, but carnivores more broadly. It was a powerful reminder: what animals eat in the wild is more than a menu—it’s a blueprint for survival.
A similar case involved peregrine falcons at The Peregrine Fund’s breeding facility. Chicks were failing to hatch, showing signs of vitamin E deficiency. Though the adults were eating whole prey (quail), their blood levels of vitamin E were far below those of wild falcons. Initially, we injected vitamin E directly into the feeder quail—up to 50,000 birds a year—but this clearly wasn’t sustainable from a labor perspective. So we reformulated the quail’s diet instead, enriching it with vitamin E. The result? Healthy chicks and a conservation success story that helped remove peregrines from the endangered species list.
The key takeaway here applies to animals and humans alike: what your food eats matters. Trophic-level effects ripple through ecosystems. Nutrition is not just about what goes into your mouth; it’s about the entire food chain.
Browsing Rhinos and the Complexity of Plant-Based Diets
Not all species rely on meat. Browsing rhinos—Sumatran and black rhinos—presented an entirely different nutritional puzzle. Captive individuals suffered from fatty acid and mineral imbalances, iron overload, and antioxidant deficiencies. Our solution began in the field, analyzing native browse plants and their unique nutritional profiles.
Forage consumption lists alone are meaningless unless you understand what’s in them. We couldn’t replicate every plant in a rhino’s wild diet, but we could recreate its nutritional profile using available ingredients. That approach led to major improvements in health and longevity for these animals. In fact, such nutrient data can even inform how we designate conservation landscapes, helping assess whether habitats can truly support the species they’re intended to protect.
When Moths Disappear: The Mountain Pygmy Possum
Homemade "moth balls" made from insect meal, nut flour, eggs, and a mix of minerals and vitamins.
Then there’s the mountain pygmy possum, a tiny marsupial from Australia that emerges from hibernation to feast on bogong moths, specifically their stomachs. But after wildfires destroyed moth habitats, the possums began starving. Working with Zoos Victoria, we needed a replacement diet that could be scattered by drone in remote areas.
Luckily, someone had once analyzed bogong moth bellies. Using that data, I created a homemade version of “moth balls” from insect meal, nut flour, eggs, and a mix of minerals and vitamins. We tested the formula on local wildlife and then adapted it with an Australian manufacturer using ingredients sourced locally. The new diet worked. It was even honored with a national conservation award—proof that informed improvisation can save lives.
From Wildlife to Livestock: Scaling Up Sustainability
Fast forward several decades and more than 200 scientific publications later, and I’m now at World Wildlife Fund leading sustainable feed innovations. The same principles that helped endangered species now guide how we nourish livestock—only now, we’re operating at scale.
Sustainable feeding systems must protect the planet while nourishing animals and people. That includes:
1. Circularity and No-Waste Feeding
Food loss doesn’t have to be landfill-bound. Through WWF’s work in Zimbabwe, for example, we collect hotel and restaurant leftovers to feed black soldier fly larvae. These larvae are then dried and ground into protein-rich feed for poultry, fish, and pigs— as a replacement ingredient with lower environmental impact. Their frass (waste) becomes biofertilizer, and the animals and herbs raised in this system can be purchased back into the hospitality sector. It’s a closed-loop system with virtually no waste.
2. Regenerative Principles
To ensure a healthy next generation—plant or animal—we must focus on the health of the foundations they rely on. Just as animals depend on nutrition, plants depend on soil. Regenerative agriculture protects and restores soil ecosystems. Maintaining soil structure, protecting it from erosion, and supporting its microbial life are key to improving nutrient availability and reducing input costs. Practices like cover cropping, no-till farming, crop rotation, and integrating trees into pasture systems all help build more resilient, biodiverse landscapes while conserving water, storing carbon, and boosting long-term productivity.
3. Novel Ingredients
WWF is exploring seaweed as a sustainable feed ingredient as it requires no land, water, or fertilizer, sequesters carbon, and can reduce methane emissions from livestock. Still, it poses challenges: nutrient content varies by species, season, and handling, and may include both beneficial as well as potentially imbalanced nutrients. Detailed analysis and R&D are needed to ensure consistency, safety, and effectiveness. Infrastructure and regulatory hurdles also need addressing for broader adoption. Yet, studies across species show seaweed can enhance productivity, immunity, gut health, and antioxidant status even in small amounts. Alternative ingredients like these deserve careful scientific exploration.
4. Responsible Sourcing
Sustainable feed choices should consider environmental impacts such as greenhouse gas emissions, land and water use, energy demands, nutrient runoff, and effects on soil carbon and biodiversity. Precision feeding—tailored to growth stage, season, or breed—can reduce waste and improve efficiency. Using local or climate-adapted ingredients, like drought-tolerant sorghum in place of corn, can maintain productivity while lowering costs, reducing methane, and improving resilience—especially in regions facing water stress or heat extremes.
Learning from Nature
The nutritional challenges I faced feeding endangered species are not so different from those in today’s livestock and aquaculture systems. In both cases, we’re trying to feed animals efficiently, humanely, and sustainably—often without access to the exact ingredients they’d find in nature.
Our planet’s resources are finite. As we feed a growing human population, we must also reduce conflict with wildlife, prevent ecosystem degradation, and make our food systems more resilient. Nature already provides the answers. We just need to observe, understand, and apply what we learn. Because sometimes, saving a species or even saving the planet starts with what’s on the menu.