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A Noisy Night in Las Aves de Barlovento

It is midnight in Las Aves de Barlovento (the Venezuelan out islands). By the light of the moon I can see boobies flying around, chasing and squabbling with each other. There is a mix of Brown Boobies and Red-footed Boobies and they are noisy. The word raucous comes to mind. Boobies are gregarious by nature and this colony has many noisy juveniles and courting adults. It is hard to describe the calls of the Red-footed Booby, but here it goes … ghaaow or try grack, grack grack! At the nest you can hear grunts, honks and hisses.

In the daylight it is easy to pick out the Red-footed Boobies from the Brown Boobies (All at Sea, April 2009). Red-footed Booby adults have bright red feet and the juveniles have pink feet, all a have pale blue bill and skin around the eye, with pink at the base of the bill. Their plumage is a bit confusing because there are several color variations called morphs that range from individuals that are all white, except for blackish on the wing, to individuals that are entirely dark brown. Individuals representing several morphs can breed in a single colony. These are the smallest of more than half a dozen booby species and they breed in the tropical islands in Hawaii, Caribbean Sea, Atlantic, Pacific and Indian Oceans, and seas north of Australia.

Red-footed Boobies are strong flyers and can travel up to 90 miles in search of food. They often hunt in large groups of mixed seabirds. Boobies are well adapted for diving and have long bills, lean and aerodynamic bodies, closeable nostrils, and long wings which they wrap around their bodies before entering the water. They locate their food by sight from the air and make spectacular plunges with speeds up to 60 mph into the water when they spot fish. At night, they may dive for schooling squid that are visible because of their phosphorescence. All boobies and many other sea birds carry their prey back to their nest in their stomachs and regurgitate it for the young. On the way back to the nest they might run a gauntlet of Magnificent Frigate birds that will chase the boobies, grab onto a wing or tail and give them a vigorous shake in hopes of getting the booby to regurgitate the fish. That is one of many ways the Magnificent Frigate birds steal food from other birds (All at Sea, November 2009).

Boobies are curious by nature and have learned to follow fishing boats for fish scraps. The juveniles are especially curious and bold and confuse lures with fish scraps. We caught a juvenile Brown Booby as we approached the Aves. Fortunately the booby let go of his prize green plastic squid as we reeled it in. Once in the water, the birds use their webbed feet to aid swimming. Although agile in the air, they can be clumsy when taking off or landing. Boobies earn their name from their antics in landing and taking off and their natural curiosity.

Red-footed Boobies build stick nests in trees or bushes and nest in large colonies. They lay one chalky blue egg, which is incubated by both adults for 44-46 days. They wrap their highly vascularized webbed feet around the egg to keep it warm during incubation. It may take up to three months before the young fly, and five months before they make extensive flights. The low reproduction rate is balanced by these birds' long lifespan, which has been reported to be up to 40 years. Red-footed Booby pairs may remain together over several seasons. They perform elaborate greeting rituals, including harsh squawks and the male's display of his blue throat. When not breeding these boobies spend most of the time at sea, and are rarely seen away from breeding colonies.

The Red-footed Booby is not globally threatened because it is so widely dispersed. The biggest threats are coastal development and a fishing industry that compete for their food source.

Devi Sharp is a retired wildlife biologist and is exploring the birds of the Caribbean with her husband, Hunter, on their sailboat, Arctic Tern. Chuck Shipley is a former professor of computer science and an avid amateur photographer. He and his wife Barbara live aboard their trawler Tusen Takk II in the Caribbean.

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