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A pelican flies over Walvis Bay in Namibia. See more ­pictures of birds.

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Does a pelican's bill hold more than its belly can?

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­You're strolling along the b­each when a large, peculiar-looking bird catches your eye. There are lots of gulls and sandpipers around, but this particular bird really stands out. It's rather squat and looks awkward as it walks around, but its bill is incredibly long compared to the rest of its body. When the bird spreads its wings, you see that it has a large wingspan. As it flies out over the water, you notice something ever stranger -- a loose bag of skin hanging around its neck. Even if you know nothing else about pelicans, you'll probably immediately recognize one by its most distinctive feature: the bag of skin, called a gular pouch, which stretches from the lower half of its bill to its neck.

­There are either seven or eight species of pelican, depending on who you ask (some scientists classify the Peruvian pelican as a subspecies of the brown pelican). All pelicans have a similar awkward appearance (at least, until you see them take flight) but they vary in their size, color, territory and behavior. Some species nest in trees, while others build crude nests on the ground or in rocks. Pelicans can weigh as little as 6 pounds (2.72 kilograms) and as much as 30 pounds (13.61 kilograms), and they live on every continent except Antarctica.

Pelicans are very social animals, building their nests in colonies. The brown pelican is unusual because it's the only species to feed by diving headfirst into the water, or plunge diving. Most other pelicans work together to herd schools of fish into shallow water. Then they dive in and scoop up the fish, often all at the same time.

Now that you know more about the pelican in general, let's get up close and personal with its most prominent feature.

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Get a load of the gular pouch on that one.

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Follow that Bill: Pelican Features

­Pelicans are part of the order Pelecaniformes, which includes around 50 species of waterbirds. These birds are distinguished from other orders by their four webbed toes, the fact that they breathe through their mouths instead of nares (nostrils), and their tendency to feed on marine animals. The other big thing they have in common is the gular skin mentioned on the previous page. Some birds take the concept one step further. Instead of just a bare patch of skin, they have a loose, stretchy pouch that they can expand and contract. The great frigate bird, another member of the order, puffs up its gular pouch with air during courtship displays. But only the pelican has such a big pouch, and it's the only one of its order to use its pouch to catch meals. A pelican's lower mandible (the bottom half of its bill) is basically just a frame around the pouch.

Another unique feature is the hook at the tip of the pelican's upper mandible (the top half of its bill), which helps grab onto particularly slippery or wiggly fish. After locating and scooping up its prey, the pelican opens its bill and slowly contracts its pouch to empty out the water and keep the fish inside. Then, with a jerk of the bird's head, the fish slides down the ­hatch. If a fish is particularly large, the pelican might manipulate it so that the fish goes down head first, which helps keep it from getting stuck. A pelican can't eat or fly away if its pouch is still full of water, so the draining process is very important. By bending its neck, it can even turn its pouch inside out. The winner for sheer bill size is the Australian pelican -- its bill can be up to one and a half feet (about half a meter) long.

The title of this article was prompted by a famous limerick written by humorist Dixon Lanier Merritt in 1910:

Oh, a wondrous bird is the pelican! His bill holds more than his belican. He can take in his beak Enough food for a week. But I'm darned if I know how the helican.

A pelican's bill does have a larger capacity than its stomach. A pelican's stomach can hold up to 1 gallon (3.79 liters), while its pouch can hold up to 3 gallons (11.36 liters). That adds up to the equivalent of 8 pounds (3.63 kilograms) in the stomach and about 24 pounds (10.89 kilograms) in the pouch. While a pelican might technically be able to take enough food in its bill for a week, it doesn't store food there. If it catches more fish than it can eat at one time, the excess is stored in the pelican's esophagus.

Save the Pelican

Some pelican species are at risk of becoming extinct. The Dalmatian pelican is listed as "vulnerable" on the International Union for the Conservation of Nature’s Red List of Threatened Species [source: IUCN]. Conservation efforts are underway. 

Some species that live in the United States, like the brown pelican, dwindled in number due to the effects of the pesticide DDT, which made their eggs’ shells too fragile to survive.  The brown pelican is currently on the U.S. Fish & Wildlife Game Service's Endangered Species List for populations in California and Nevada, but may be soon removed due to a strong comeback.

Pelican Feeding: What's on the Menu?

­While most pelicans eat fish exclusively, they can be opportunistic feeders, eating lizards, frogs, crabs and lobsters. Pelicans have even been observed eating smaller birds, sometimes scooping up water in order to drown them before swallowing. In 2006, a photographer in London's St. James Park recorded an extraordinary sight. The five pelicans currently living in the park are fed a diet of fish, but apparently that wasn't enough for one of them. A pelican picked up a pigeon from the sidewalk and swallowed it, to the shock and amazement of park visitors. Since the incident, other people claimed to have seen the St. James Park pelicans eating pigeons. A spokesperson for the Royal Society for the Protection of Birds said that this behavior was highly unusual and likely attributed to the birds' contact with people and its more urban environment.

­Sometimes pelicans tag along with other birds tracking their prey in the water, stealing the fish right from under them. They themselves are victims of pirating on occasion. It can take a few seconds for a pelican to drain all the water out of its pouch, during which time a gull -- often standing on the pelican's head and pecking it as a distraction -- darts into its open bill and steals the fish.

Aside from catching their prey, pelicans use their bill for other things. During courtship, male pelicans often stretch out and flap their pouches and clap their bills repeatedly. They may also lash out at rivals and other threats with the sharp hook at the end. Baby chicks are fed by both parents, who regurgitate partially digested fish for them to eat. Chicks that are old enough to eat whole fish but not yet ready to hunt may be seen "fishing" for dinner inside their parents' pouches. Pelicans that live in warm climates sometimes open their bills and flap their pouches in order to cool down.

Fossil records show that pelicans have been around for more than 40 million years, so regardless of how weird the pouch might seem to us, it's served the bird well. With the continued efforts of conservationists, hopefully pelicans will be around for a long time and continue to amaze and intrigue us -- especially if they mostly lay off snacking on pigeons.

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Sources

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  • Audubon: Birds & Sciencehttp://www.audubon.org/bird/
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