Birds News 06-08

01 17 08 Mirror Neurons Involved in Vocal Learning in Birds

Researchers at Duke University identifed a certain class of neuron in the Swamp Sparrow (Melospiza georgiana) forebrain that has similar responses when the bird sings a series of notes, and when it hears a similar sequence sung by another bird. They conclude that these neurons function similarly to so-called morror neurons in primates.

12 20 07 Birdsong Variation Enables Learning

Birdsong is a complex learned skill requiring precise and rapid vocal control. In some species, including the Bengalese finch, adults sing highly stereotyped songs. But by working within the range of normal variability, and in tiny increments, researchers can push the song in a particular direction. Natural variation, the researchers suggest, may help birds fine tune their songs.

03 19 07 Nuthatches eavesdrop on variations in chickadee mobbing alarm calls

Many animals recognize the alarm calls produced by other species, but the amount of information they glean from these eavesdropped signals is unknown. We previously showed that black-capped chickadees (Poecile atricapillus) have a sophisticated alarm call system in which they encode complex information about the size and risk of potential predators in variations of a single type of mobbing alarm call. Here we show experimentally that red-breasted nuthatches (Sitta canadensis) respond appropriately to subtle variations of these heterospecific "chick-a-dee" alarm calls, thereby evidencing that they have gained important information about potential predators in their environment. This study demonstrates a previously unsuspected level of discrimination in intertaxon eavesdropping. Abstract © 2007 PNAS. University of Washington press release includes photos and calls.

04 27 06 Starlings Learn ‘Human-Only’ Syntax Patterns

In a series of experiments with European starlings (Sturnus vulgaris) using warbles and rattles in place of words, the birds learned to recognize a recursive-type grammar from a simpler grammar. Chomskian linguists have theorized that the ability to process recursive grammar forms the computational core of a uniquely human language facility. The research also contrasts with previous experiments showing that tamarin monkeys could not recognize recursive grammar.

03 27 06 Birdsong Probed With X-Ray Movies

X-ray movies of singing cardinals reveal that songbirds adjust their song’s tonal qualities by actively changing the shape of their upper vocal tract in a cyclical manner.

01 28 06 In Whipbird Duets, Female Song Varies

Bird biologists have long known that male song varies from region to region. But less is known about female song. Now researchers in Canada and Australia have shown that in eastern whipbirds (Psophodes olivaceus), female songs vary distinctly from region to region, while male songs remain highly consistent.
D. J. Mennill, of the University of Windsor in Ontario, Canada, has posted an interactive web page with spectrograms and audio recordings with a link to the research paper in the Journal of Avian Biology.
CBC’s Quirks & Quarks radio show, 01 28 06, features an interview with Mennill.

A male Swamp Sparrow (Melospiza georgiana).

Swamp Sparrows and mirror neurons

Photo © 2008 Rob Lachlan