OK, so this is a tad late. I actually took the photo below on art’s birthday, 17 January 2010 (art is 1,000,047).
Just now got it all processed, being somewhat busy with work and that play thing.
This is a photo from the Murray Road overpass at Hwy 26, just west of Portland.
From the perspective that I first saw them, the pigeons had arrayed themselves along the top three of five wires that ran across the south section of the ramp.
They appeared to me to be presenting a tune for art’s birthday.

Trying to decode the tune, I first assigned a value to the various head positions – tucked, straight up or leaning (surprisingly, if leaning, their heads all tilted in the same direction).
One was in flight.

I then made a couple alterations using a graphic editor to get the photo to more closely represent a staff.
This was fairly easy to do since the pigeons had already chosen a five-wire/line location.

I next tried to assign note values to the birds’ positions. I at first thought whole notes for the tucked/hunched birds, an eighth note for the leaning (like the flag on an eighth), etc. but that made it all seem a bit drawn out and dirge-like. I instead bumped it up such that the bird in flight became a half note, the tucked/hunched birds were quarter notes, the leaners were eighths and the straight-ups were assigned a value of a sixteenth.
I’m not that great at figuring rests, ties and all so I got it as close as I could on a basic treble staff (being birds I figured they’d go for the higher line work rather than the lower).

Once I had the tune I then processed the sound file, removing rests and spaces, to get it to more closely match the original photo.
I did the same to the staff. It now looks more like a Satie score. It sounds a bit like one as well.

The tune.
Happy birthday, art. Thank you, pigeons.
[Other birthday year celebrations can be found here]
otomo yoshihide
korekyojinn
haino, kawabata & yoshida
Jamie – you are brilliant!
Thanks, Lea.