JOHANNESBURG (AP) — Botswana, long viewed as a rare refuge for African elephants, is coming under increasing threat from poachers.Poachers are killing elephants in the southern African country in increasing numbers after wiping out large numbers of elephants in nearby Zambia and Angola, a conservation group said.The Elephants Without Borders group and wildlife officials in Botswana have conducted half of a national elephant census and so far have counted nearly 90 "fresh and recent" carcasses of poached elephants, group director Mike Chase said in an email.A similar census in 2014 found just nine carcasses, according to Chase. Botswana has an estimated 130,000 elephants, the most of any country in Africa.The reported increase in elephant poaching in Botswana could reflect a trend in which poachers move into new territories as conditions become more difficult in regions where they usually operate.Those conditions could include a dearth of elephants to kill after widespread poaching, or crackdowns on trafficking syndicates in some cases.Tanzania's Selous region, for example, was heavily hit by elephant poachers but recent data indicates that the killing has slowed. Even so, killings intensified around the same time in Mozambique's Niassa reserve to the south, which is linked to the Selous by a wildlife corridor.The fight against elephant poaching has made some gains, including a ban on the ivory trade in China, the world's biggest consumer.