Bird song could isolate species: UBC research

September 13, 2017

The Cinnamon Becard is one of the species UBC researchers investigated. Credit: Andy Reago and Chrissy McClarren.

Two birds that look the same, but have songs so different they can't recognize each other, should be considered distinct species, suggests new University of British Columbia research.

“Songs are important for birds and who they choose to mate with,” said Benjamin Freeman, a Banting postdoctoral fellow in the department of zoology at UBC. “Birds evolve different songs and we wanted to find out which populations are so different in song that they should be considered different species.”

Among the 72 related populations of Central and South American birds the researchers tested, they found evidence for 21 new species. Organisms that mate and create an offspring that can go on to reproduce are considered to be part of the same species but there are a number of naturally occurring barriers, like geographic location or behaviour, that can prevent similar organisms from mingling.

In the study, UBC and Cornell University biologists examined how different populations of birds respond to each other’s songs. In the tropical forests of Central and South America where the vegetation is dense, birds rely heavily on song to claim their territory and let other birds know where they are. For this experiment, the researchers conducted playback experiments by hanging wireless speakers in the trees and broadcasting songs from related subspecies and then observing how the birds responded. If the birds continued on with their natural behaviour and ignored the speaker and sound, it indicated that they distinguished the songs. They did not feel like another bird was encroaching on their territory and trying to mate with their partner. If the bird got angry and started to try and kick the “intruder” out, it indicated they recognized the song. Historically, scientists have identified new species by finding birds that look different enough or occupy different geographic locations.

“It’s interesting that with one study in one year, we came up with good evidence that there are 21 new species that authorities should recognize,” said Freeman. “We know so much about birds but this demonstrates that we still have a lot to learn.” This research is part of a larger pursuit to learn about the evolution of bird songs and why birds develop different songs. “As a birdwatcher in tropical forests, you have no choice but to get interested in songs,” said Freeman.

“As you walk through the forest, you hear 25 birds for every one you see. As a biologist, I wanted to know – is it important that the birds sing differently and is it a little important or a lot important?” Freeman and his colleagues will submit these findings to a committee of ornithologists who are responsible for naming and recognizing bird species of South America.

Bird song samples and images

Cinnamon Becard and Chestnut-crowned Becard

Research findings: These two populations look different and have somewhat different songs but birds west of the Andes (Cinnamon Becard) respond to song from the Amazon Basin (Chestnut-crowned Becard). 

Cinnamon Becard - Central America, western Colombia and western Ecuador
Photo: https://macaulaylibrary.org/asset/46001051
Song: https://macaulaylibrary.org/audio/184776

Chestnut-crowned Becard - Amazon

Photo: https://macaulaylibrary.org/asset/40353171
Song: https://macaulaylibrary.org/audio/62573

Golden-bellied Warbler

These two populations look similar but sing differently. The birds in western Ecuador ignore song from eastern Peru. They should be classified as distinct species.

Population A from western Ecuador (Pacific slope)
Photo: https://macaulaylibrary.org/asset/56593091
Song: https://macaulaylibrary.org/asset/31431731

Population B from eastern Peru (Amazon basin)
Photo: https://macaulaylibrary.org/asset/35480631
Song: https://macaulaylibrary.org/audio/147345


For more information, contact…

Chris Balma

balma@science.ubc.ca
  • Biodiversity
  • Biology
  • Evolution
  • Zoology

Musqueam First Nation land acknowledegement

UBC Science acknowledges that the UBC Point Grey campus is situated on the traditional, ancestral, and unceded territory of the xʷməθkʷəy̓əm.

Learn more: Musqueam First Nation

Faculty of Science

Office of the Dean, Earth Sciences Building
2178–2207 Main Mall
Vancouver, BC Canada
V6T 1Z4
UBC Crest The official logo of the University of British Columbia. Urgent Message An exclamation mark in a speech bubble. Arrow An arrow indicating direction. Arrow in Circle An arrow indicating direction. A bookmark An ribbon to indicate a special marker. Calendar A calendar. Caret An arrowhead indicating direction. Time A clock. Chats Two speech clouds. External link An arrow pointing up and to the right. Facebook The logo for the Facebook social media service. A Facemask The medical facemask. Information The letter 'i' in a circle. Instagram The logo for the Instagram social media service. Linkedin The logo for the LinkedIn social media service. Lock, closed A closed padlock. Lock, open An open padlock. Location Pin A map location pin. Mail An envelope. Mask A protective face mask. Menu Three horizontal lines indicating a menu. Minus A minus sign. Money A money bill. Telephone An antique telephone. Plus A plus symbol indicating more or the ability to add. RSS Curved lines indicating information transfer. Search A magnifying glass. Arrow indicating share action A directional arrow. Twitter The logo for the Twitter social media service. Youtube The logo for the YouTube video sharing service.