Catalina bison on birth control

AVALON, Calif., Nov. 20 (UPI) -- California's Catalina Island has put its famous bison on birth control to produce a healthier and less environmentally damaging herd, officials said.

The herd, which now numbers fewer than 200, ideally would contain about 150 bison, descendants of 14 shipped to the island in 1924 for the silent movie "The Vanishing American."

Ten years ago, as many as 500 bison roamed the rugged island's 76 square miles. The Catalina Island Conservancy, which oversees the herd, began reducing the population when it was determined island bison were smaller than mainland bison, lacked a sufficient food source and were prone to open sores, the Los Angeles Times reported Friday.

Some were sent for slaughter or to other breeding programs before conservancy officials settled on a contraceptive vaccine that will still allow the animals to mate but not become pregnant, conservancy spokesman Carlos de la Rosa said.

"For bison in love, this means romance without responsibilities," he said.