About how long do male emperor penguins fast while incubating an egg?

Male emperor penguins fast for about 115 days while incubating the egg and waiting for the female to return.

After the female lays a single egg, she carefully transfers it to the male’s feet. He covers it with a warm fold of abdominal skin called a brood pouch, then remains on the sea ice through the Antarctic winter while the female travels to the ocean to feed.

During this period, males may lose around 40 percent of their body mass. They huddle together to conserve heat in temperatures that can fall below −50 °C, while severe winds make conditions even harsher.

The female usually returns around hatching time with food stored in her digestive tract. She then feeds the chick, allowing the exhausted male to walk to the sea and feed.