This is my first contribution.
First go to where the chickens are in Lower City here on the map,
Next you need to use your Feint ability on a chicken. Sometimes they don't run in the right direction, so it may take a few tries for it to run like this (through the wall).
As the chicken goes through the wall, use Shadowstep to follow it through. You will end up on the other side. You can mount up on a flying mount and fly around under Shattrath.
Pic from below: