A Kettle of Vultures

BirdNote^®

A Kettle of Vultures

Written by Conor Gearin

This is BirdNote. 

    [Gusts of wind]

The sight of hundreds of vultures slowly circling overhead might seem pretty ominous. But most of the time, it just means the vultures are on their way somewhere else. 

In the daytime, hot air rises as the sun heats the ground. The rising column of air is called a thermal, and it’s the perfect way for a Turkey Vulture to hitch a ride.

Like an elevator to the skies, the thermal gently wafts the vultures upward. They move in a slowly ascending spiral around the thermal, rarely flapping and instead coasting on the breeze. When many vultures ride the same thermal, it’s called a kettle.

During raptor migration, kettles can swell with many different raptor species, like this Swainson’s Hawk. 

    [Swainson’s Hawk call]

Hawks see the swirling vultures and join in, taking the opportunity to save their energy.

The air current lifts the birds hundreds or thousands of feet in the air before petering out. Finally, the raptors leave the thermal and gliiiide downward for miles — often far enough to take them to another thermal. 

[Swainson’s Hawk call] 

Thermals make raptor migration a breeze — and a one-of-a-kind spectacle for observers on the ground.

For BirdNote, I’m Michael Stein.
Support for BirdNote is provided by Jim and Birte Falconer from Seattle, Washington, and generous listeners around the world.

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Senior Producer: John Kessler
Producer: Mark Bramhill
Managing Editor: Jazzi Johnson
Managing Producer: Conor Gearin
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Swainson’s Hawk ML 112977571 recorded by Julia Wittmann.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2023 BirdNote   April 2023         
Narrator: Michael Stein

ID# kettle-01-2023-04-11    kettle-01