Something was stealing the Bullock brothers’ food.
Joe, Douglas, and Sam Bullock had moved to Washington’s San Juan Islands in the early 1980s and set to work creating a food forest. They built up their property’s soil and planted fruit trees, nut trees, and hundreds of other species, all calculated to boost the biological diversity and lushness of this once-scrubby, blackberry-entangled parcel. A decade later, walnut trees and bamboo groves shaded the paths. Plums, peaches, cherries, and apples hung in thick festoons from spreading branches, and beneath them flowers, berries, edible greens, and soil-building plants sprawled over every inch of earth. The Bullocks had created a self-renewing ecosystem that fed their families and visitors, furnished nursery stock for their landscaping business, and sheltered local wildlife.
One edge of their property bordered a wetland reclaimed a few years before from abandoned farmland. At the marsh’s edge, cattails grew in thick stands. Young cattail shoots are a delicious wild food, and for several springs and summers the brothers had harvested the baby shoots, steamed or sautéed them, and added them to meals. But one year they couldn’t find any shoots, only tough mature cattail stalks. Their natural food source had dried up, and the brothers wanted to know why. A close look at the marsh revealed that some animal was gnawing the tender shoots off at the waterline. The thieves were thorough. Nothing remained for the Bullock brothers and their families.
The culprit was quickly spotted. “We’d noticed that as the bog matured and became more productive, the muskrat population was really taking off,” Douglas Bullock told me. The brothers had built garden beds that extended into the marsh, copying an idea from the ancient Aztecs. They had created peninsulas by piling straw and branches that reached out like fingers from the shoreline, covered them with rich bog muck, and planted these selfwatering garden beds, called chinampas, with food and wildlife plants. The local animals, already enjoying the new wetland, responded to the enhanced habitat of the chinampas with explosive breeding. Ducks, kingfishers, herons, and other water birds now abounded, and so did muskrats. “Suddenly the bog looked like a busy harbor, criss-crossed with muskrat wakes,” Douglas said. Whole flotillas of muskrats were tunneling into the rich soil along the marsh edge and nibbling down the cattail shoots. The less agile humans couldn’t compete with the industrious rodents.
The brothers lamented the loss of their wild food, yet refused to begin exterminating the culprits. “For one thing, we weren’t going to kill off the wildlife that we ourselves had attracted,” Douglas explained. “For another, we could have shot muskrats for weeks, and they’d just breed right back again. The habitat was too good.”
A cattail-less season or two went by. Then, suddenly the tasty shoots were back, and the once-busy “harbor” was more tranquil. The muskrat population had dwindled. What had happened?
“Otters moved in,” Douglas said. “The muskrats were a great new food source. We’d never seen otters here before. More than otters showed up, too. We got other predators: bald eagles, hawks, owls. They cleaned up.” Instead of futilely trying to trap the fast-breeding muskrats, the Bullocks sat back and let nature do the job. The brothers merely provided a rich, diverse habitat where a vigorous food web—one that included predators—could emerge and right imbalances, such as a horde of ravenous muskrats.