Avian Air Sacs
Birds have a very efficient breathing system which makes use of their lungs, but also utilizes air sacs (7-12, depending on species) within the bird’s body. Common Loons use their air sacs for more than respiration, however. By changing the amount of air in the sacs, loons can vary their depth while resting in water. A deep breath fills the sacs with air and produces high flotation. During dives, in addition to compressing their feathers(which forces air out from between them), loons decrease the amount of air in their air sacs by exhaling. The ability to deflate their air sacs also allows loons to quietly sink below the water’s surface in order to make it easier for their young chicks to climb aboard.
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Naturally Curious with Mary Holland 
Whoa! Who knew?
July 13, 2015 at 8:03 am
Fascinating!
July 13, 2015 at 8:12 am
Evolution favors good parenting!
July 13, 2015 at 8:55 am
So true, Kathie! Interestingly, in a culture that seemingly favors safety over all else, most of my friends do not expect to be grandparents – or are pleasantly surprised when they do!
Does get complicated since there are too many humans. Perhaps there IS a connection. It’s been said “Nature always bats last.”
July 14, 2015 at 7:56 am