Sunday, June 7, 2009

RB grosbeak profile

Rose-breasted grosbeaks are obviously a fairly charismatic member of our avifauna; they're frequently the bird brought up by people at work when they find out I'm a birder.

When they first arrive from their migration at the end of April and the end of May they hit the feeders pretty hard re-fueling before they really work on setting up territories. Many of the first spring birds still show their age with prominent brown edges to the mantle and un-moulted brown feathers in the wings.
This adult male still has scant brown edging to the fresh back feathers yet to wear off but has solidly black coverts and flight feathers.

And the classic full adult male...
Despite being really common we somehow nearly missed this species on a summer big day back in Washtenaw and was seen by only one team member (Lathe if I remember right).

Of course in addition to being a striking bird, it's also a solid songster. Here's sonograms made from a bird I video'd while atlasing back in Washtenaw a few years ago. These are 5 songs from the same male.
The first 3 phrases are essentially the same but after that it's slightly more variable, though the middle 3 songs are fairly similar for the first 3 seconds. There's a general pattern that the phrases alternate between a higher pitch and a lower pitch though as the song progresses the phrases seem to center around a more similar pitch. I'm not sure if there's a pattern to the variation in each phrase as to how many times it changes the pitch in each phrase or not.

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