In Australia, kangaroos appear to have been killed by an extinct breed of marsupial. Also: Millions of dead sardines are found in Redondo Beach, Cal.; and a colony of blue herons flee their Minnesota nests.
Hundreds of dead crocodiles are found along the Victoria River in Australia; a long-standing belief in mule infertility comes into question when a female mule gives birth in Morocco; and sharks are found dead along the U.S. West Coast.
Mysteries of nature are examined using a combination of detective work and science. First up: a highway beast in Minnesota; a sudden rush of salmon in Canada; strange patches of sand in Southern Africa.