When it comes to heroic dads, it’s hard to outdo the emperor penguin. But a newly released study suggests the reality may fall short of the legend.

Male emperor penguins are famous for going without food for up to 115 days while they mate and then shelter a solitary egg from the brutal winter winds. Dramatic footage of the semiannual ritual, which begins with a 100-kilometer Antarctic trek to an inland breeding ground, helped make 2005’s “March of the Penguins” one of the highest grossing documentaries of all time.

But researchers who visited a different colony say they witnessed the animals taking breaks from their breeding duties to go fishing in the winter darkness, challenging the popular notion that they are nature’s most dedicated dads.

The behavior was witnessed at Antarctica’s Cape Washington in late May 1998 — after breeding season had begun and the sun had permanently set for the winter — by a team led by Gerald L. Kooyman, a marine biologist at the Scripps Institution of Oceanography at the University of California, San Diego.