Each year humpback whales like this one along Australia’s east coast migrate from feeding grounds in Antarctica to breed in tropical waters. That, at any rate, is what biologists always believed. Yet when biologist Peter Corkeron at James Cook University in Queensland and Miranda Brown at the University of Cape Town in South Africa surveyed humpbacks recently, the migratory groups turned out to be 75 percent male. Where were the missing females? Corkeron says that young females may spend all year in the Antarctic, venturing north only when sexually mature. Chilly as it sounds, staying in cold waters year-round may be less energetically taxing for a young whale than migrating north to warmer waters. In any case, Corkeron’s results suggest that counts of eastern Australian humpbacks (the whales, now said to number about 2,800, have been making a comeback since dwindling to perhaps 200 in the sixties) need to be adjusted--upward. The estimate has to get knocked up about 25 percent because we’re counting only 75 percent of the population, Corkeron says. Of the great whales, humpbacks have had a hell of a lot of scientific work done on them, yet here’s this really basic bit of information about them that’s just coming out now.