We had the same problem the cardinal came Back every spring for 5 years. We came home one day and had red feathers all over the place. A hawk took care of Ivan the cardinal came Back.
I've had this problem at different locations, with different vehicles. Holographic Reflective Bird tape has worked for me in the past. Our local Kroger uses Bird B Gone - Reflect-A-Bird - Reflective Spinning Deterrents, and that seems to work also. Falconry is another option.
We live in the trees & have this problem every spring; you can try folding in your mirrors and/or putting a towel in the areas that your bird likes. However, for us, it's usually 1 specific bird and we either need offer it an alternative spot to perch adjacent to the truck (usually they will choose the same few spots and cycle between them; including the truck). If it lasts more than a few weeks, then a pellet gun will ultimately solve the problem.