英语听力：自然百科 Mystery Pelican Die-off in Calif 神秘的塘鹅死亡事件

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The birds, some of them dead, have been spotted⁵ from Washington State, to Baja California in Mexico.

 

"People are finding them in unusual places, and they are finding these birds are landing in the middle of the roads--some of them are getting hit by cars. There have been reports of birds landing in people’s backyards, which is very unusual behavior for these birds."

 

The pelican³ started appearing late last month in Southern California. The International Bird Rescue Research Center has received dozens of birds at two Californian facilities.

 

"They are coming in very thin and bit disoriented, usually hypothermic. "

 

They also have bruise¹ inside their pouches⁶ and many of the birds' feet have been swollen⁷. Typically, this time of the year there is a significant die-off of young brown pelicans. But marine⁸ biologists say they are seeing a larger-than-normal die-off of adults, and some researchers suspect the corporate⁹ is a naturally occuring toxin¹⁰ found in algae¹¹.

 

"In this particular area over the last three to four years, we’ve seen a regular occurrence, typically in the spring, of a particular group of alga that's capable of producing a very powerful neurotoxin called 'domoic acid'. Through the consumption of those algae, it gets into food chains, into small fishes such as anchovies¹² and sardines¹³ and any organism alike. A pelican eating that material can acquire enough of it that it actually causes neurological distress¹⁴ or even death. "

 

While disorientation is a common symptom among birds poisoned by domoic acid, the pelican’s other symptoms don’t fit their profile. So far, there are no concrete answers. Meanwhile, volunteers are nursing the feather patients.

 

"We are providing them with IV fluids, oral fluids, food, medication if necessary, and getting them eating on their own. "

 

The California brown pelican is a sub-species of the brown pelican. Over-hunting and DDT poisoning caused brown pelican populations to plummet¹⁵ during the first half of the 20th century. And by the early 1970s the birds were all but gone. After DDT was banned in the US in 1972, the species made a dramatic comeback.

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