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Birds: Seahawk

Shocker: There’s no such thing as a “seahawk!” Tell that to Seattle.

The Washington franchise might spell it as one word, but biologists don’t. In fact, they don’t even use the term to refer to one particular species. Biologists use the name sea hawk to refer to either an osprey or a skua (itself a term that covers a group of seven related species of seabirds). Both groups share a number of characteristics, including a heavy fish-based diet.

Augur Hawk

The Seattle Seahawks’ mascot is actually a hawk from Africa, not a bird that fishes in the sea. That’s pro football marketing for you. Before every home game, the team releases a trained raptor to fly out of the tunnel in front of the players, leading them onto the field and getting the crowd excited for the game. The winged mascot is an augur hawk (or augur buzzard), and not a seafaring species, so technically, it cannot be called a sea hawk at all.

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David Knutson with Taima, the team’s mascot

According to David Knutson, the Seahawks’ falconer, for authenticity sake he originally wanted to train an osprey to be the team mascot. But the U.S. Fish and Wildlife service prohibited him from using a native American bird for commercial purposes. So instead, Knutson ordered an augur hawk hatchling—which has markings similar to an osprey—from St. Louis’ World Bird Sanctuary and he trained it to deal with the noise and chaos of the rabid Seattle Seahawk 12th man football fans.[1]

Osprey

It is hard to believe that osprey were at one time endangered. A victim in the ’60s of DDT, as chronicled by Rachel Carson,[2] the shells of offspring were too soft to withstand the weight of the parents in the incubation process and the offspring died. Only after years of trial and error was adequate DDT removed from pesticides and then from the waters of rivers and bays to help with the come-back. Then began the slow reintroduced of the osprey. With the addition of many tall nesting boxes along rivers and beaches, the species gradually returned to their native nesting areas.

Today, thanks to massive conservation efforts, the range of the main osprey species (Pandion haliaetus) covers every continent except Antarctica. A different species, the eastern osprey, lives in Australia. Although they hunt over water, ospreys generally nest on land, within a few miles of either the ocean or a body of fresh water. Unlike most bird species, they are remarkably widespread, and even more surprising, nearly all these widely dispersed ospreys (except Australia’s eastern osprey) are part of one species.

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Osprey building a nest in spring

Ospreys that live in temperate climates migrate to the tropics for the winter, before heading back to their home area for the summer breeding season. Other ospreys live in the tropics year-round, but also return to the specific nesting grounds (the same ones where they were born) each summer for breeding. The migration starts in April and May in North America.

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(Image via USGS)

Its’ in the talons

Most other hawks and falcons have their talons arranged in a static pattern: three in the front, and one angled towards the back. But ospreys, similar to owls, have a unique configuration that lets them slide their toes back and forth, so they can create a two-and-two talon configuration (as shown in the USGS figure above). This helps them more firmly grip the slippery, tubular-shaped fish as they fly through the air. If you have ever seen an osprey carrying a fish, they frequently turn the fish to a position that is parallel to its flying direction, which is helpful for aerodynamic reasons.

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The predatory birds typically fly between 50 and 100 feet above the water before spotting a shallow-swimming fish (such as pike, carp, salmon or trout) and diving in for the catch. To avoid getting water up their noses, they have long-slitted nostrils that they can close voluntarily—one of the adaptations that allows them to consume a diet made up of 99 percent fish.

 Ospreys usually mate for life

When the male osprey reaches its third birthday, he returns to his summer breeding ground and claims a nesting spot. Once established he begins performing an elaborate flight ritual overhead—often flying in a wave pattern while clutching a fish or nesting material in his talons. He will perform many hours of these feats to attract a mate. A female responds to his flight by landing at the nesting spot and eating the fish he supplies to her. Afterward, they begin building a nest together out of sticks, twigs, seaweed and other materials. And when they find a mate, it is usually for the rest of their lives. Once bonded, the pair reunites every mating season for the next few decades. On average, an osprey will live about 30 years. Only searching out other mates, when one of the pair dies.

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Fossils found in southern California show that ospreys were around in the Mid-Miocene, which occurred between 15 to 11 million years ago. Although the particular species found in California have since gone extinct, they were recognizably osprey-like and assigned to their genus.

In the native lore, the story goes that if a fish looked up at an osprey in flight, it would be somehow mesmerized by the sight of it. This would cause the fish to give itself up to the predator. This is a belief referenced in Act IV of Shakespeare’s Coriolanus: “I think he’ll be to Rome/As is the osprey to the fish, who takes it/By sovereignty of nature.”

Skua

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Pomarine Skua

A pomarine skua is frequently called a sea hawk, as are several others in the skua species. Unlike ospreys, skuas obtain much of their fish diet through a less noble hunting strategy: kleptoparasitism. This means that a skua will wait until a gull, tern or other bird catches a fish, then chase after it and attack it, forcing it to eventually drop its catch so the skua can steal it.

Unlike the Bald Eagle, which chased down smaller birds to capture its fish, skuas are rather brazen in their extortion attempts—in some cases, successfully stealing from a bird that is up to three times their weight. During the winter, as much as 95 percent of a skua’s diet can be obtained through theft.

The osprey and skua are the real sea hawks, but you will have to convince the US Fish & Wildlife to allow one of those birds to be the mascot for the Seattle Seahawks.

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Skua demonstrating kleptoparasitism

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[1] The bulk of this Witness Post comes from an article by Joseph Stromberg, a science reporter for Vox.com. He was previously a digital reporter for Smithsonian. This story was covered by Joseph Stromberg in the Smithsonian.com, “14 Fun Facts about Seahawks,” 1/31/2014.

[2] Carson, Rachel (1962). Silent Spring. Houghton, Mifflin, Harcourt, New York.