When Josh Daskin traveled to Mozambique’s Gorongosa National Park in 2012, its iconic large animals were returning from the brink of extinction. Gorongosa, among Africa’s most spectacular wildlife preserves until the 1970s, had been devastated by an anti-colonial war of liberation followed by a ghastly 15-year civil war — a one-two punch that exterminated more than 90 percent of the park’s wildlife.