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Bird Poop and Fish Eggs

What’s small, alive, and hardy enough to survive passage through a swan’s gut?
© David Larson View Large

Scientists have long suspected that bird poop may play a role in the dispersal of fish species to new bodies of water. After seeing a fish egg in a fecal sample from a wild Coscoroba Swan in Brazil, a scientist staged an experiment to see whether killifish eggs could endure a trip through the swan’s digestive system. Today's show is brought to you by the Bobolink Foundation.

Full Transcript



Bird Poop and Fish Eggs

Written by Monica Gokey

This is BirdNote.

Scientists have long suspected that birds play a role in introducing fish species into new bodies of water. But there wasn’t hard evidence to support that hypothesis… until recently.

[Chorus of Coscoroba Swans - Macaulay Library ML68416]

Coscoroba Swans live in the southern hemisphere, breeding at the bottommost parts of South America and then migrating north to Uruguay and Brazil. That’s where a Brazilian scientist saw something unexpected.

[Single swan squawk… as if to say, “Whaaat?” MLS 218912 :24 or :32]

He was looking at the poop of a wild Coscoroba Swan, seeking signs of invertebrate and plant life, when something else caught his eye: the egg of a killifish.

Intrigued, he designed an experiment. A research team fed captive Coscoroba Swans a grain mix laden with fish eggs. Then they waited. After being digested -- and “exiting” the swan in the bird’s feces -- a small fraction of those fish eggs were still viable.

Waterbirds: boldly “going” wherever their flyways take them… and contributing to the dispersal of other species in the process.

[Tundra Swan chatter, ML 136376]

To learn more about birds and the marvelous things they do in our world, visit us online at bird-note-dot-org.

For BirdNote, I’m Michael Stein.

Today’s show is brought to you by the Bobolink Foundation.

Producer: John Kessler
Executive Producer: Sallie Bodie
Editor: Ashley Ahearn
Associate Producer: Ellen Blackstone
Producer: Mark Bramhill
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. ML 68416 recorded by D. Finch. ML 218912 recorded by J.I. Areta. Tundra Swans, ML 136376, recorded by M. Anderson.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2020 BirdNote   May 2020     Narrator: Michael Stein

ID#  poop-03-2020-05-26    poop-03

Killifish study, Ecology, 2019,

Coscoroba is pronounced kohs-ko-RO-buh
Killifish is pronounced KILL-ee-fish