Whales' methods of communication are complicated, and not yet well understood by scientists. Listen to examples of the vast differences in sounds that whales produce in these five recordings of whale vocalizations.
Recording 1: A humpback whale recorded March 22, 2003 at Isla Socorro, Revillagigedo Archipelago, Mexico. Credit: Danielle Cholewiak, PhD., Acoustic Specialist, Stellwagen Bank National Marine Sanctuary. NOAA/NOS
Recording 2: A humpback whale. Credit: Sofie Ban Parijs, Northeast Fisheries Science Center, NOAA Fisheries Service.
Recording 3: A sperm whale echolocating. Courtesy of the Scripps Whale Scoustic Laboratory.
Recording 4: A right whale. Courtesy of the Scripps Whale Scoustic Laboratory.
Recording 5: Another right whale. Courtesy of the Scripps Whale Scoustic Laboratory.
John Wesley Powell's epic journey into the unknown Grand Canyon was filled with adventure as his team mapped the Colorado River for the first time.
The story of the farmers who dreamed of prosperity and lived through ten years of drought, dust, disease and death.
Native Alaskans, oil company representatives, environmentalists, politicians, and others tell the story of the 800-mile pipeline.
A personal story of one family's dramatic effort to hold onto their family farm in Iowa as massive foreclosures sweep the nation in the 1990s.
Robert Marshall, Aldo Leopold and Howard Zahniser dedicated their lives to protect the shrinking American wilderness.
The life of the legendary photographer, known best for his black and white images of the wilderness of the American West.
High on a granite cliff in South Dakota's Black Hills tower the huge carved faces of four American presidents: George Washington, Thomas Jefferson, Abraham Lincoln, and Theodore Roosevelt.
The New Deal program CCC put three million young men to work in camps across America.