Well this is really sad...

[Bogertophis]

This almost sounds like something either a child or a person with a severe mental illness like downs syndrome (or another illness that affects cognition) might do...i.e. "make the birds look pretty for the holidays" etc.. I think if someone had outright malicious intent, the birds might be tortured or something besides tying tinsel on them. Sad situation for sure.

Except that a child or mentally-challenged adult is unlikely to have the skills necessary to do this, especially to so many. And they tend to have others looking out for
them to keep them out of trouble. (Many years ago, I worked with mentally-challenged adults as a part-time job while I was going to college.)

Can't rule out an adult with a mental-problem though, as it does seem to be an obsession with holiday decor...?