High-pitched bird call, Colorado front range (US) (1 Viewer)

[tenex]

I occasionally hear this bird locally (even in winter) but have only spotted it once (I think!) in a treetop in low evening light without binos. Medium-small perching bird, call is a single note so very high in pitch that it seems hard to locate, and I think first of some metallic squeak rather than a bird. Any ideas on ID? Thanks.

 

[The Bird Nuts]

Cedar Waxwing?

 

[The Bird Nuts]

Or maybe an American Robin? https://www.xeno-canto.org/323031

 

[tenex]

I see both here, robins more often than waxwings, but suspect waxwing in this case because the sound is simpler (less dynamic?) and never mixed with more interesting calls. Thanks for pointing out xeno-canto. This recording is an excellent match: https://www.xeno-canto.org/185609