Frank and John Craighead

The brothers began collecting and identifying animals and plants they found alongside the Potomac and soon expanded their interests to birds and hawks.

During the 1950s, the Craighead brothers expanded their work to other animals, including many species living in and around Yellowstone, and eventually separated.

[2] In 1959 their careers merged again, this time to begin a 12-year study of grizzly bears in Yellowstone since the animals were considered threatened by increased human activity.

The twin brothers, almost identical to one another, spent much of their time collecting animals and plants along the banks of the Potomac while out of school, but their breakthrough with wildlife came in 1927, when they raised a baby owl at their home.

[7] At age 20, the brothers wrote their first article for National Geographic Society, published in the July 1937 issue, Adventures with Birds of Prey.

[8] During World War II, R. S. Dharmakumarsinhji, an Indian prince living in Bhavnagar who was impressed by the Craigheads' articles invited the brothers to visit India.

Frank would drive from Pennsylvania, arriving in Yellowstone early in the spring and staying until late in the fall when the bears denned.

Frank added indoor plumbing to his cabin on Antelope Flats, and he and Esther moved to Moose, Wyoming permanently.

The fact that many bears died at age five or six after human encounters persuaded the Craigheads to ask park officials to enforce animal rules more strictly.

After educating the public about how vital rivers were for water, recreation and fishing, they created the Craighead Environmental Research Institute in 1955 for the "protection and study of wildlife and wilderness.

"[7] The Institute paved the way for clean water protection and President Johnson signing the National Wild and Scenic Rivers bill of 1965.

Meanwhile, John had married Margaret Smith, a mountain climber and daughter of a Grand Teton National Park ranger.

Frank and Esther, and John and Margaret built identical log cabins on their property in Moose, and began families.

[5] While Frank was completing his various field studies during the late 1940s and early 1950s, he and Esther had three children - Lance, Charlie, and Jana.