Birds successfully adapt songs to change in landscape
May 21st, 2009 - 1:26 pm ICT by IANSWashington, May 21 (IANS) As vegetation reclaimed formerly cleared land in California, Oregon and Washington over the last 35 years, male white-crowned sparrows lowered their pitch and slowed down their singing so that their love songs would carry better through heavier foliage.
“This is the first time that anyone has shown that bird songs can shift with rapid changes in habitat,” observed biologist Elizabeth Derryberry, who made the finding as part of her dissertation research at Duke University.
The physics is clear, but the biology is a little less certain. A lower, slower song suffers less reverberation in denser foliage and will be heard more accurately.
In turn, that means it is more likely to be copied by young males who are choosing which song they will learn. Over generations, that should cause the song to slow down and drop in pitch as the foliage changes.
She compared recordings of individual birds in 15 different areas with some nearly forgotten recordings made at the same spots in the seventies by a California Academy of Sciences researcher.
She found that the musical pitch and speed of the trill portion of the sparrows’ short songs had dropped considerably. “I was really surprised to find that songs had changed in a similar way in so many different populations.”
She then used archival aerial photography to see how the foliage had changed in a subset of those spots, and found that the one population whose song hadn’t slowed down lived in an area where the foliage hadn’t changed either.
In the short term however, Derryberry doesn’t know whether the clearer song wins better territories or mates, although she does know that these changes in song do affect both male and female behaviour.
The results add to a growing body of evidence that the acoustic and visual communications of animals change with their habitat, said a Duke release.
“Given how much the world’s habitats are changing, this is sort of an unexpected but useful factor to monitor,” Derryberry said.
She’s now testing the broader effects of ecology on song evolution in birds across areas of South America where habitat may be changing due to deforestation and global warming.
This study will appear in the July edition of American Naturalist.
- Sparrows' love tunes change with the landscape - May 21, 2009
- Sparrows twittering louder to be heard - Apr 03, 2012
- Alterations in bird songs linked to habitat change - Jun 13, 2009
- Weather turns birds into more flexible singers - Aug 05, 2012
- Sparrow decline indicates serious environmental change: Experts - May 09, 2012
- Modern sparrows sing louder to be heard - Apr 05, 2012
- Are house sparrows being driven away? (March 20 is World Sparrow Day) - Mar 19, 2012
- City noises have forced songbirds to sing a different tune - Jan 06, 2011
- Nightingales may be extinct in 30 years! - May 30, 2011
- Scientists uncovering origins of singing mice - Aug 12, 2012
- Croaks help frogs locate mates with matching DNA - Dec 28, 2011
- Where have all the sparrows gone? (With Images) (March 20 is World House Sparrow Day) - Mar 19, 2011
- Sparrows 'learn songs by twitter' - Oct 21, 2009
- This year celebrate 'Sparrow Holi' - Mar 20, 2011
- House sparrows facing extinction in Punjab - Nov 15, 2009
Tags: aerial photography, biologist, bird songs, body of evidence, california academy of sciences, california oregon, derryberry, dissertation research, duke university, female behaviour, foliage, land in california, love songs, musical pitch, rapid changes, reverberation, short songs, sparrows, trill, visual communications