Aves Non Grata - The Blue-footed Booby

I pushed my sister off the roof our house once. I meant no harm. We were simply filming what we expected would be the big winner on America’s Funniest Videos. When her cue came and she didn’t jump, I pushed her. That’s what big brothers do. She was fine. Anyway I have two more sisters where that one came from.

Booby with chick © Pete Corradino

Blue-footed Boobies (Sula nebouxii) are occasional visitors to the United States but they nest primarily along the Pacific from Mexico south to Peru. They are opportunistic nesters, laying between 1-3 eggs on the ground inside a curious white ring. The eggs are laid and incubated asynchronously and hatch in the order in which they were laid. If times are good, everyone gets fed and fledged. When food is scare, competition sets in among the hatchlings who participate in siblicide. They kill their own brothers and sisters. In theory, the first hatchling has the upper hand, or wing as it were, which they use to push the younger siblings out of the nest. In some cases they can push them off a cliff edge but here’s where the mysterious white ring comes into play. What looks like a monochromatic circle of spin art is a fecal ring. The female will rotate around the center of the nest and squirt feces and uric acid in a scattershot pattern.

White fecal ring around nest © Pete Corradino

During a trip to Ecuador I had an opportunity to see the nesting behaviors and artistic displays firsthand. The Blue-footed Boobies will let you approach and seemingly don’t even recognize your presence until you step across the magic white fecal line (which I did not do out of respect for the wildlife). Now facing a threat, her pointed beak becomes all business. Anything within the circle conversely must be protected.

© Pete Corradino

A hatchling does not understand this. They understand hunger and survival. When they push their siblings, hatched or unhatched, across the magic line, the female booby suddenly earns her name. Beyond the line, her young become aves non grata.

© Pete Corradino

It had never occurred to me that with one less mouth to feed I’d have a greater opportunity for more food. In fact our incident on the roof had the opposite effect. No dessert that night and no more access to the roof.  

Pacific Piracy - The Magnificent Frigatebird

© Pete Corradino

To take from others that which is not yours would seem an easy way to acquire any number of things. Treasure comes to mind. Regurgitated squid as well. As long as men have sailed the oceans there have been pirates plundering the belongings of others and as long as birds have taken to the skies, there have been certain species that would steal rather than hunt on their own. The colonial roosting, coast-dwelling Magnificent Frigatebird (Fregata magnificens) is one such bird. While they are quite capable of plucking flying fish and other pelagic species from the ocean’s surface, they have the unscrupulous habit of pestering fellow avian species into reluctantly giving up their meals.

© Pete Corradino

Many of Ecuador’s islands, from the far flung Galapagos (over 500 miles off the South American coast) to Isla de la Plata (just a few miles from shore) were famed pirate hideouts. A stone throw from the rocky cliffs of Islamar is Isla Salango, home to colonies of Blue-footed Boobies (Sulane bouxii), Magnificent Frigatebirds and Brown Pelicans (Pelecanus occidentalis). The island’s high cliffs, draped in tropical vegetation and capped with stone turrets provide excellent habitat safe from many terrestrial predators, but the Blue-footed Boobies must keep a watchful eye on their piratical island neighbors. Frigatebirds target boobies returning to the island with an obvious crop full of recently captured food. The frigates are light-weight, aerial acrobats, weighing in at no more than three and a half pounds with a wingspan nearing six feet. Their ability to pursue and harass boobies and other coastal birds provides them an additional food source besides scouring the seas themselves.

© Pete Corradino

As I stand on the mainland of Islamar, I watch the long-beaked frigates gliding on an imperceptible wind. For hours they drift back and forth across this span of sea. Beyond the limits of my vision, males return to the island with sticks and vegetation for the females who build the nest for a singular egg that both will tend to for nearly two months. The young will remain with the mother for up to eighteen months and by age five they will have learned that the entire ocean contains treasure to feast upon, even if someone else found it first.