The "Flying Squirrel" Operation's Unexpected Success 70 Years Ago

In the 1940s, experts employed an unusual relocation method using planes and parachutes to transport beavers to more suitable habitats.

Beavers are beloved animals for many of us. They are not only adorable but also industrious in building dams that help keep their ecosystems healthy. Beaver dams slow down the flow of rivers and streams, reduce soil erosion, and the ponds formed by these dams replenish groundwater supplies. Beaver ponds become homes for many other species, and the dams act as natural filters for flowing water, improving water quality downstream.

However, beaver dams can also raise water temperatures upstream and deplete oxygen levels in the long term. Furthermore, beavers can damage crops and gardens. According to National Geographic, this was the primary complaint from families moving from large cities to southwestern Idaho in the years immediately following World War II.

The method of relocating beavers using planes and parachutes. (Video: Time).

As Americans moved away from cities and deeper into the wilderness, the Idaho Fish and Game Department (IFG) recognized that the beaver problem they had been trying to manage since the 1930s was only going to worsen. However, killing beavers was not a preferred option as they provide valuable “services” to the ecosystem, creating an environment that enhances water quality and biodiversity while reducing erosion risks. Consequently, they needed relocation methods to address the overpopulation of beavers in certain areas, taking them to more suitable habitats.

Central Idaho contains a protected area, the Frank Church-River of No Return Wilderness. Within this area lies the Chamberlain Basin, a place rich in forests and featuring a prominent creek. It seemed like the perfect location for relocating beavers. However, the question remained: how would they get them there?

Elmo W. Heter, an employee of the Fish and Game Department, wrote in an article for the Journal of Wildlife Management: “Traditional transport methods in this case would be very costly, labor-intensive, time-consuming, and result in high mortality rates.” Factors affecting beaver mortality during such trips include: the scent of beavers disturbing the horses carrying them; capture and transport could make many beavers agitated, leading to aggression; beavers have poor thermal tolerance when out of water; and temperature stress and harsh transport conditions could lead to some beavers refusing to eat after a while.

Beavers can damage crops and gardens.

After discussing the challenges of transporting beavers, Elmo W. Heter began to devise a better method. He concluded that it was best to relocate them in mid-summer; their migration season would be over, allowing them time to adapt to their new home. He also learned from previous relocation efforts that it was better to move young beavers, ideally four at a time with one male and three females or two males and two females. But the question remained: how would the beavers be transported?

In a 1950 document titled “Relocating Beavers by Plane and Parachute”, Elmo Heter explained why more traditional relocation methods had failed. Heter described these methods as laborious, time-consuming, and costly, with high mortality rates among beavers.

For instance, after being loaded onto a horse, beavers were exposed to direct sunlight for several days, preventing them from eating, making them increasingly aggressive, and leading to many fatalities. “Clearly, a faster, cheaper, and safer transport method is essential. The use of planes and parachutes met that requirement,” he wrote.

Before releasing the beavers, IFG tested various weights to determine that a 7-meter synthetic parachute used in World War II was the most suitable. Pairs of beavers were placed into boxes and transported using a single parachute. The advantages of this method included reducing the number of parachutes by half, while also decreasing the likelihood of beavers leaving the landing area, as having companions seemed to encourage them to stay.

Pairs of beavers were placed into boxes and transported using a single parachute.

“An older male beaver we affectionately named Geronimo fell several times during takeoff. Each time he climbed out of the box, someone would come to catch him. Eventually, he resigned himself, and as soon as we approached, he crawled back into his box and was ready to fly again,” Heter wrote.

“Geronimo had priority on the first flight to the new land, accompanied by three young females. Even upon arrival, he remained in the box for quite a while while the females busily explored the new environment. However, his group was later reported to be thriving,” he added.

Geronimo’s inaugural flight paved the way for 76 other beavers in the fall of 1948, with only one reported fatality, likely due to the beaver’s own actions. After the drop, a loose cable created a small gap in the box, allowing the beaver to poke its head out and climb up. According to Heter, if the animal had stayed put, everything would have been fine, but for some reason, at 23 meters above the ground, it jumped or fell out of the box.

Experts later analyzed the parachute method for releasing beavers and found it cost about $16 less per beaver compared to the old method, while also reducing mortality rates and the number of work hours required to complete the journey.