Elephants are being slaughtered across Africa because Nigeria, Senegal, and Ivory Coast have ignored the global ban on the ivory trade, environmental groups said this week. The World Wildlife Fund and the anti-poaching group Traffic said in a joint report that the three countries, which have all but wiped out their own elephant populations, were operating illegal ivory markets that encouraged poachers in other countries. Elephants are endangered, and selling the ivory from their tusks was banned in 1989, with a few exceptions for antique figurines. But tons of new ivory has been flowing into Nigeria, Senegal, and Ivory Coast, where it is carved into intricate ornaments and labeled antique. The report faulted the countries for a lack of political will to end the trade. The world elephant population now numbers around half a million, down from more than 1 million in 1980.