Wood Swingset Blue Prints Birds Will Rest On Swingset (made Of Wood) And Poop On The Slide/seats, Etc. What Can I Do To Stop This?

Birds will rest on swingset (made of wood) and poop on the slide/seats, etc. What can I do to stop this? - wood swingset blue prints

Is there any type of material that can be placed on the bar above the runway and change, there will be a deterrent effect on birds?