Hello Marcia,
One possibly is that it has molted a large wing feather. We have heard this very noticeable and different than usual sound each year and found it to to be a missing wing. It always surprises me when I first hear it.
We have several Anna's year around at our feeders. They are currently also feeding on sap from fresh Sapsucker wells on our birch tree, beginning eight days ago.
Dan Reiff
MI


> On Sep 29, 2018, at 3:58 PM, Marcia Ian <gnudle at icloud.com> wrote:

>

> One of the Anna's hummingbirds at our feeder yesterday made a strange clacking sound in flight, resembling the sound made by a playing card inserted into the spokes of a kid's bike for the purpose. Any thoughts as to what might be the cause?

>

> Marcia Ian

> Bellingham

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