Bird Watcher's General Store

Oil Rig Lights Confuse Migrating Birds
04/07/17


Dear Bird Folks,

I’ve just finished watching a show on the National Geographic station called Blitzkrieg Sharks, and I think you might be interested in it. The show focuses on tiger sharks and their habit of eating, of all things, songbirds. Have you seen it?

– Matt, Brewster, MA

Thanks, Matt,

Thank you for telling me about the TV show. Since 1975, when I finally moved into my own home, my parents still phoned me every few days. They didn’t call to inquire about my new job or my health, but instead they felt a need to tell me what they had just watched on television. Each week I got an update on the most recent episode of The Love Boat, so thanks for keeping my parents’ tradition alive. Even though Blitzkrieg Sharks isn’t quite the same as The Love Boat, I appreciate the effort.

After receiving your note I decided to check out the show you mentioned; by doing so, I discovered two things. First, my cable box has something called “On Demand”. Ever hear of it? If I hit the right buttons, my TV will play just about any show at any time. Cool beans! Why didn’t my parents ever call and tell me about this? Second, the television version of National Geographic is pretty cheesy. The magazine we all remember was both beautiful and scholarly. This shark show, on the other hand, was totally hokey. (“Blitzkrieg”? Really?) The narrator yelled an endless stream of dramatic catchphrases, which was like listening to a monster truck rally ad. However, in between all the clichés and yelling, was actually a pretty interesting story. Tiger sharks are really and truly eating songbirds. (It should be pointed out that while this seems like one of my annual fabricated columns, the shark/songbird story is real, but not a danger to us. In other words, you don’t have to search the horizon for fins before you go out and fill your birdfeeder.)

In 2009, Marcus Drymon, a shark researcher in the Gulf of Mexico, was startled to discover that the stomach contents of a recently caught tiger shark contained bird feathers. When I first heard they were examining stomach contents, I thought this couldn’t be good for the shark. I expected to see something gross and gory, like that license plate scene in Jaws. Instead, they simply pumped water into the shark and rinsed out its stomach, like they were rinsing out a birdbath. As the shark’s stomach contents poured out, I was surprised that I didn’t see any fish heads, or tin cans, or car parts or old surfers. There were just lots and lots of feathers. At first, Marcus wasn’t really surprised; after all, sharks are opportunistic feeders. They will eat anything they can catch, including careless gulls, pelicans and ducks. But the feathers in this shark belonged to woodland birds. Somehow tiger sharks were catching and eating woodpeckers, thrushes and warblers. How was this possible? Was the old Saturday Night Live Land Shark making a comeback? Are sharks stalking our backyards? Stay tuned for the exciting conclusion to this story, right after a word from Oxiclean. (Sorry. That’s what they did on TV.)

Before releasing the tiger shark back into the water, Marcus’s team attached a satellite-tracking device to it. Over the coming months they caught and released several more feather-filled sharks and began tracking their movements. I’ll tell you what they found out right after this. (This next part is all about birds and has nothing to do with sharks, or Oxiclean.) Each spring and fall, millions of birds cross the Gulf of Mexico on their biannual migration. The Gulf contains nothing but endless miles of seawater…and an estimated 4,000 oil platforms. During the day these platforms serve as tiny avian rest areas. (Even though the platforms are rusted steel and smelly oil, they are still better than the rest areas found along the highways in Massachusetts.) When the sun goes down, however, these same platforms become a huge problem. Like moths around a flame, migrating birds become disoriented by the platforms’ bright lights. Some migrants die when they crash into the metal structures. Others spend hours circling the lights, until they drop into the sea from exhaustion. It is thought that an estimated 200,000 birds are lost to these platforms annually. For a while researchers were allowed onto the platforms in order to study the problem. But when the grim evidence started rolling in, the oil execs decided this nasty truth was better kept quiet. Birders are now kept away. However, there are some bird lovers the oil people can’t keep away…tiger sharks.

Marcus Drymon’s data suggests that sharks spend much of their time (especially during migration) foraging around the platforms and scooping up birds that have fallen into the water. Can anything be done to help the birds? On its North Sea platforms, a Dutch oil company is experimenting with green colored lights that might be less problematic. So far, the results have been promising (although I don’t think the sharks are happy about it).

Thanks for suggesting that I watch the shark program, Matt. It really was very interesting. I’m just glad the sharks are only eating songbirds in the ocean, and not the ones on land. I have enough trouble dealing with raccoons and squirrels.




Artwork by Catherine Clark


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