01 June 2009

Bird Songs, Individual Differences

Yesterday I sat at a picnic table in a local regional park for a couple of hours 'studying' the bird songs around me and thinking about how best to describe them. A Yellow-rumped Warbler called the whole time and I took quite a good set of field notes of his song - as in, I could actually interpret them when I got home and almost recall the song in my head.

I wrote:
phrase of two parts:
  • first part consisting of a monotone or slightly ascending trill, moderate speed. Trill equal to a twitter, very slightly buzzed, mostly clear tones;

  • second part, executed immediately after first part, higher pitched, ascending, variable warble of slightly shorter duration than first part (warble = more than two tones) consisting of a variable ascending trill.
Then! I played some warbler calls LOUD on my mp3 player through little portable external speakers I pack around with me (I don't like headphones cuz they get tangled with my bino strap and my eye-glasses cord that I need so I don't lose my glasses when I take them off to read because I'm getting old, you know).

Anyway, the Yellow-rumped Warbler changed its song! After singing the same song for an hour, it changed, seemingly, in response to my play-back! The first part was noticeably higher pitched and definitely ascending and the second part was even shorter than before. Then this new version, Song B, slowly evolved back into Song A, with the second part going back to the Song A sooner than the first part. It repeated Song A again several times, then burst into song B, which again morphed back to song A over several repetitions.

Today, as I sit writing this, with my office window open, a Yellow-rumped Warbler is calling from a nearby fir tree.

Is it singing the exact same song as the one in the park yesterday? No, not really! This song is not in two discernable parts - the monotone trill grading into a more warbling ascending trill at the end. This one is more just a single phrase with the whole thing starting with the monotone trill, upwards, to end in almost individual cheeps. What can I say - it's hell to be detail oriented, and probably boring to read.

2 comments:

  1. In "the 1st part," you are describing a sound I heard today while walking Rusty my dog. A very proud small warbler was doing that monotone trill! I recognized his as different from the other bird songs in the neighborhood. So glad to come across your blog. I was thinking I'd like to find out exactly what type of bird he is, just by his song, thought it may be a needle in a haystack. Thanks for the hope I'll find our what bird he is. Best, Mary

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  2. That's great I have been of some help! Don't forget to check it out at Macaulay Library and listen to the different Yellow-rump sounds. I'm still working out how to describe the difference between a Chipping Sparrow's trill / chatter and a warbler's trill.
    Cheers, Kestrel

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