Gannets, tough heads, and offshore oil drilling.

On a beach on the Isle of Palms, South Carolina:

gannet wing

…an immature Northern Gannet, washed ashore after a sea burial. Cause of death unknown. This bird’s brown plumage identifies it as a first-year bird, hatched this spring. Adults are white (seen here in my visit to a gannet colony in Scotland); second- and third-year birds are white splashed with brown.

North America hosts only six breeding colonies, all in Canada (three in the Gulf of St. Lawrence and three in coastal Newfoundland). Adults and youngsters alike head to southern waters for the winter, feeding offshore before returning to their rocky breeding sites in April. Overwinter survival for adults is often higher than 90%, but young birds have a harder time.

Gannets are plunge-divers, folding their wings and arrowing into the water, head-first. They use the momentum of the dive to swoop into schools of fish. If they miss on the first strike, they oar the water with their wings as they twist through the water after prey. Their bodies are well adapted to this punchy way of getting lunch. Air pockets and strong shoulder bones cushion the body. The conical head and chest offer little resistance to the flow of water or air. A study of Cape gannets found that they pierced the ocean’s skin like needles, barely decelerating as they hit. The beak has no nostrils, just a tiny slit that closes tight when water pushes against it. Gannet eyes are directed forward in a binocular gaze, protected by a movable transparent membrane. One tenth of a second after immersion, gannet eye lenses compensate for the changed refraction of light and snap into underwater mode.

North American gannets comprise about one quarter of the world population. The rest breed in Northern Europe and winter off the coast of Africa. After many decades of over-hunting and disturbance, American colonies have lately been growing. Aerial surveys of nesting sites indicate a annual increase of 4.4% from 1984 to 2009. After the Deepwater Horizon disaster, though, some breeding populations dipped. After the spill, gannets were the third most common bird species recovered (dead, sick, or oiled) by rescuers. Because the explosion and spill happened in late April, most adult gannets had left the Gulf. Immature birds lingered and were caught.

Now, the Atlantic waters off the southeastern coast are slated to be opened for drilling, despite opposition from the many human residents of the coast whose interests coincide with those of seabirds.

Photo and bird-finding credits: Katie Lehman and Eva Miller.

2 thoughts on “Gannets, tough heads, and offshore oil drilling.

  1. johnboulton10

    Hi, according to Dr Wiki there are about 50 000 breeding pairs in Australia and NZ of the Australasian gannet (Morus serrator or Sula bassana), but mostly in NZ. Here on the Pacific east coast of OZ I see gannets diving for fish on a daily basis, often many at a time over a shoal.
    There are good underwater shots in Attenborough films of them coming through the surface like an arrow and catching fish. Here juvenile shearwaters (mutton birds) die in large numbers when exhausted from flying against a persistent headwind during migration, and get washed up on the beach. John

    Reply
    1. David George Haskell Post author

      Thank you, John. Seeing that many at a time must be spectacular. At the Bass Rock they are mostly ferrying food and wheeling, not engaging in group plunge-dives. I’ve seen some of the Attenborough footage: getting so close to the give is quite a view.

      Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s