Back in 2010 , scientists were monitoring a shark population on the Mississippi - Alabama perimeter . They had hauled up a small tiger shark to tag when something strange find : It retch up feathers . A desoxyribonucleic acid analysis revealed that the shark had eaten a brown thrasher , a stippled migratory songbird related to the mockingbird .
Further depth psychology unveil that this was n’t just an marooned incident — a pregnant percentage of shark stomach contents revealed the clay of common backyard bird , and , surprisingly , only one coinage of waterfowl . Thestudy , write in the journal Ecology , demo that food web are more complex than you might think , and might even offer prediction about shark conduct .
Scientists analyzed Panthera tigris shark belly content from 2010 to 2018 , and found bird remain every year except for 2014 , in 41 of the 105 shark examined . Nineteen of those shark were babies . There were 11 bird species symbolise : barn swallow , eastern kingbird , house wren , common yellowthroat , marsh wren , eastern meadowlark , swamp dunnock , brown fox shark , white - winged peacenik , scandalmongering bellied sapsucker , and American coot . These are species that birdwatchers in the U.S. look ahead to see during the yearly fowl migration each spring and fall .
A tiger shark in the Bahamas.Photo: Albert kok (Wikimedia Commons)
You might wonder how the sharks end up run through these country - dwelling birds , and why there were n’t any sea shuttlecock — the researchers did , too . They look up each of the mintage on eBird , the Cornell University - run community scientific discipline database where birdwatchers log their sightings , to see when the raspberry were anticipate to pass over the Gulf . The time when each hoot ’s remains were regain coincided nearly utterly with the peak of the bird ’s fall migration geological period in the cases of all but two metal money .
As to how the birds stop up in the ocean , that ’s not exculpated . The scientist speculated that unexpected regretful weather in the declivity might drive many migrator into the sea , where they ’re ineffective to swim and terminate up dying ; past studies have document evidence of these aggregate mortality events . That would explain why there were n’t many seabirds found in the shark remains — the eaten bird could n’t get away from the wave , unlike sea bird , which are practiced able to navigate ocean condition .
This is n’t the first time that chick remains have been bump in shark bellies , survey author Auriel Fournier from Mississippi State Universitytweeted . But what ’s exciting about this work is that it cover sharks over time , allow for researchers to connect the shark behaviour to bird deportment . They noted that the fall bird migration happens around the same fourth dimension as elevation in the number of baby tiger sharks , who are generally are n’t quick to hound on their own . Foraging on the dead migratory birds might be an important substitute food source until they become capable predator .
A brown thrasher at Green-Wood Cemetery in Brooklyn. Perhaps this bird’s own grave will be inside a shark stomach.Photo: Ryan F. Mandelbaum
Though this is just a specific instance of a surprising species interaction , it ’s yetanother exampleof the surprising connections between species on the Earth . I just wish I did n’t have to think about all of those bushed doll .
BiologybirdmodoBirdsEcologyScienceSharks
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