Posted: 24/09/2014 at 00:23
A perching place, what's the point of that when you can plant something which will be of use to bees, or other insects or provide food for birds? For instance a wild cherry, rather than an ornamental cherry would be suitable. Elderberry would be suitable too.
Alders are pretty big trees. Have you thought of trained fruit trees along your fences?
I think you need to do some more research, and certainly ignore any tree that will grow to 10 metres!