Nearly a dozen wild horses have died in the first 10 days of a big mustang roundup in Nevada, deaths that a Las Vegas congresswoman is calling tragic proof of the urgent need to outlaw helicopters to capture the animals on federal land. The 11 deaths so far include five young foals, four horses with broken necks and a stallion with a snapped rear leg that was chased by a helicopter and horseback rider as it tried to flee on three legs for 35 minutes before it was euthanized, according to witnesses. The horse that broke the leg jumping over a trap fence last Wednesday was a lead Palomino stallion called “Mr. Sunshine” by those who'd watched him roam wild over the years southeast of Elko.