I too have a very noisy and odd sounding Anna's hummingbird in the yard. It sounds like a kid with a playing card in his bicycle spokes.

Back in March and early April I had 14 Rufous hummers about for a couple weeks then all but a couple left. My pair of year-round Anna's were not miffed at all with the interlopers. Both Anna's and Rufous nested and now the kids are around along with one pair of adults of each specie.

The buzzing male Anna's 'noise' seems to be less now than a week ago so it may have something to do with molting.

Mary Hrudkaj
Belfair/Tahuya