Defending Economic Livelihoods and Threatened Animals Act or the DELTA Act This bill directs the Department of State and the U.S. Agency for International Development to work with Angola, Botswana, Namibia, and neighboring countries to develop a strategy to: (1) promote responsible natural resource and wildlife management practices in the greater Okavango River Basin, (2) protect migration routes of elephants and other threatened wildlife species, (3) combat wildlife poaching and trafficking, (4) address local health needs, and (5) catalyze economic growth. The strategy shall also involve partnerships with donors, the private sector, and local, regional, and nongovernmental entities.