Blue-footed Booby

Blue-footed Boobies are tropical seabirds that breed on the Galapagos Islands.  They  barely build nests, laying their eggs in a shallow scrape on the ground.  The scrape is surrounded by a ring of guano.  I have read that this ring is caused by the incubating booby always facing the sun.  I notice, however, that this booby is not facing the sun.  The guano ring may discourage predators or vermin.  Stephen Jay Gould, in his collection of essays, Hen's Teeth and Horse's Toes, writes that the ring serves another purpose: recognition of young.  If a young bird, for whatever reason, trespasses out of the ring, the adult not only ceases to care for it but will also  prevent the young from returning to the nest.

In the Galapagos, we also found nesting Red-footed Boobies.  You can tell the photo below is the red-footed species because it does not nest on the ground--it is up in the mangrove bushes--and, by the way, this booby sports red feet.