Thursday, July 22, 2010
Before albatross fledglings (the grown-up chicks) leave Midway Atoll National Wildlife Refuge, they have to get rid of any stuff they have in their stomachs that can't be digested. Their stomachs pack it all together into what's called a "bolus." Then the bolus gets thrown up and out of the chick's wide-open beak.
Can you see the difference in the neck size between these two Laysan Albatross? The left-hand albatross is trying to pass up a bolus. Notice how much wider its neck is; it must be very uncomfortable!
For the first 5 months or so of their lives, albatross chicks are fed food which their parents bring them from the ocean. Albatross especially like to eat flying fish eggs and squid; yum! But the squid mouths, called beaks, can't be digested because they're made out of tough material, sort of like a finger nail. Since flying fish eggs are usually attached to floating objects, the albatross often swallow floating volcanic rocks (called pumice) and sticks. which the fish eggs are attached to. So, squid beaks, pumice and sticks are natural parts of bolus barf.
But there are also some man-made items in boluses. This short video shows a Laysan Albatross chick throwing up a bolus, or maybe just part of one. I think you'll be surprised to see what I found inside this bolus.