They can attack a wide range of trees, including sycamore; maples, ash and beech can be badly damaged or even killed by bark stripping.
They get on the benches knocking small trees off and breaking pots in the process. They also dig up the pots and kill lots of roots. We have a problem with squirrels that may be more unusual, our garden contains 18 large fully grown oak trees all producing acorns every autumn. The squirrels are acquisitive storing animals and our soft soiled bonsai are easy digging ground. Thus every autumn squirrels prepare for winter, forget where they have stored their acorns and thus every spring we have at least one new oak tree per bonsai pot.