BirdNote; Aggressive Warblers and Climate Change

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Aggressive Warblers and Climate Change

This story aired in December 2012

Written by Todd Peterson

This is BirdNote.

The territories of Townsend’s Warblers [Song of Townsend’s Warbler] and Hermit Warblers [Song of Hermit Warbler] overlap in Washington State. Ornithologists call this overlap a “hybrid zone” where the two species interbreed.

At the Burke Museum in Seattle, specimens of Townsend’s and Hermit warblers are displayed side by side. It’s easy to see the variations in yellow and black plumage that distinguish one species from the other. The hybrids reveal characteristics of both. The birds’ markings show that the species interact, and they may also give us clues about our changing climate.

[Song of Townsend’s Warbler]

Male Townsend’s Warblers are very territorial. When a stuffed Hermit Warbler decoy was put in its territory, it ripped it to shreds. This aggressive behavior is pushing the hybrid zone south.

[Song of Townsend’s Warbler]

But what does feistiness have to do with climate change?

Rob Faucett, ornithology collections manager at the Burke, explains:

What ecologists …are anticipating is that as the climate warms and rainfall decreases …that will drive the hybrid zone northward. … so you have the concept of aggressive behavior driving the hybrid zone southward and …and we… ecologists and climate modelers are expecting that the forest types that are used by these two different species will be driving northward… and so those two different pressures will be counteracting each other…

Ten years ago or 15 years ago no one really had any idea that the collections could be used for this, yet we kept collecting and kept building the collections…. If we as a society don’t continue to build these collections, we’ll be stuck in the future with no way to answer all the new questions that are gonna arise.

Find out more at birdnote.org.

[Song/calls of Hermit warbler]

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Sounds of the birds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Song of Hermit Warbler recorded by G.A. Keller; song of Townsend’s Warbler by D.S. Herr.

Producer: John Kessler

Executive Producer: Chris Peterson

© 2012 Tune In to Nature.org December 2012 Narrator: Mary McCann

ID# SotB-warblers-01-2010-12-02