[CREWZIN]

I think the chrome will attract the birds even more-so than the black mirrors BUT it might not be able to get a good grip on the shiny chrome BUT it will try and probably scratch those also.

I'd try something like they do to the globe lights at parks (at least I've seen them down here) and stick something temporarily to the top of each mirror so it couldn't perch there.

One half of a velcro strip that you'd hardly notice (black) on the mirror top and something that will deter the bird from landing on the mirror on the other half of the velcro strip. When you come to the car just take the top half off.