I generally
appreciate birdsong as I walk around campus. However, I always find myself
grumpily thinking about strangling a bird and eating it for dinner when they
wake me up too early in the morning. But regardless of my annoyance, I usually
walk around Houston fairly amused by the chattering that goes above my head in
the form of song. But to my human ears, it all sounds like chirp chirp chirp,
if you know what I mean.
So it was to my
great surprise when I found out that birdsong has actually changed depending on
the environment. In fact, the sheer difference between the city and a forest
leads birds to have a change in bird song, and consequently in signaling. This
divergence was noted in an article that compared the songs of great tits within
the city and the forest where it found that songs changed both in duration and
also in frequencies. [1]. The great tits in noisy locations (city) sing at a
higher minimum frequency, most likely to be heard over the ever-present lower
frequency white noise of the city. Furthermore, these birds in the areas with
greater sound pollution had a restricted range in their repertoire of songs and
This study implies
that an environment changed by humans can potentially alter the communication
of a wild bird like the great tits. This amount of change in the communicative
aspect for wild birds domesticated within a city can affect breeding opportunities
and change a species' drastically. So while my own ears might be hearing chirp
chirp chirp, the population of birds in a city might actually slowly be
changing their own birdsong to something a little less diverse than expected in
the wild, which might even alter mating behaviors in the future.
[1] Slabbekoorn, H. & Peet, M. (2003). Birds Sing at a Higher Pitch in Urban Noise. Nature. 424, pg 267.
I am a Great Tit!
from http://robandmazza.blogspot.com/2011/05/chick- factor.html
Could, then, urbanization lead to speciation? If bird song is changing that much, and mating is affected, the populations might be technically isolated, right?
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