Why the Swamp Sparrow is Hitting the High Notes
Science Daily
Studying animal sounds and signals almost gives humans a look into the past of how our own communication abilities evolved over time. A good example of this is how humans and animals raise their voice when they are expressing aggressive communication, but why are some animals louder then others when they are aggressively communicating.
On January 12, 2009,Adrienne DuBois, a graduate student in the college of Arts and Sciences, conducted a study on aggressive communication at the University of Miami. DuBois’s study showed that the Swamp Sparrow has the ability to emit songs that are extremely difficult to produce during hostel situations. She believed that this meant that the Songs Birds used sophisticated vocal performances as Signals in aggressive communication.
At the end of the article Steve Norwicki, a professor at Duke University, said “By understanding what animals do in their natural environment, we get a glimpse of what their brains can do," …"In a broader sense, we can make assumptions about the way the animal brain develops to support a complex communication system."
This study shows that the Song Sparrow can communicate a threat by exerting a physically difficult high frequency. This ability to escalate their vocal performance shows scientist that the Song Sparrows brains are more sophisticated then originally believed.
Journal reference:
1. DuBois et al. Swamp sparrows modulate vocal performance in an aggressive
context. Biology Letters, 2009; 1 (-1): -1 DOI: 10.1098/rsbl.2008.0626
http://www.sciencedaily.com/releases/2009/01/090109125636.htm
-Stephen Chiricosta
Were you provided with any more information about how the study was conducted, such as whether it was a field study or took place in the laboratory? How were hostile conditions replicated, did experimenters wait for a predator to approach or did the create a recording of some sort?
ReplyDeletePosted by Heather Gore
It's incredible that most birds are able to communicate sophisticated information with such specific calls - even in an earlier blog post someone mentioned how a baby penguin's chirps are unique and identifiable by their parents.
ReplyDeleteIn this study, were the scientists able to quantify 'sophistication level' of the sparrow's brain? You mentioned that they somehow found that they were more complex then originally believed. Also, how did the aggressive signals differ from the non-aggressive signals?
Posted by Bethany Rappleyea
In addition to this very interesting finding by DuBois is another behavior that deals with avian aggression: song overlapping. This behavior is described as when a bird begins to sign his song when another bird has not completed his own (i.e. a male interrupts another male's song). It is interesting to see some of these parallels in human behavior as well. As you mentioned, speaking louder than another person may be perceived as a threat, while interrupting a person mid-sentence may also serve the same function.
ReplyDeleteIt would be an interesting study to see how birds recognized these situations to make themselves be more aggressive, or seem to be at least (if it is not an honest signal). Why would some birds see a male encroaching on their territory and not respond in such a way? Maybe these birds who are able to sing at a higher amplitude require more energy to do so and thus are more "fit". And maybe the fit males can interrupt the duds in the territory because they know they are fit and have the ability to stop him mid-sentence?
Posted by Christine Rega