behaviour of Marabou storks

What is that pink balloon on a marabou stork?

January 29th, 2012

Strikingly ugly and bald, with a thick powerful bill, the Marabou stork is unforgettable.  But what is that naked pink pouch that sometimes appears hanging under its bill?

This gular sac has two purposes: it helps keep the stork cool, as the skin has a dense concentration of blood vessels. It’s also a show-off device.  In the breeding season, the male Marabou stork inflates the sac to impress rivals and prospective partners.  The female will inflate hers in return.  They also have a second air sac, small and normally hidden by feathers at the back of the neck, which swells like a red bubble during a display.