From Ground: Thoroughly water the bird vetch plant to moisten the soil surrounding the roots. You'll then need to dig a trench around the bird vetch, being sure to dig wide and deep enough so as not to harm the root system. Once done, carefully slide the spade under the root ball and lift.
From Pot: To remove the bird vetch from a pot, first, water it well. You can then turn the pot on its side and gently pull the plant out. Be careful to hold the plant at the root ball and not by the stems or leaves to minimize damage.
From Seedling Tray: If you are transplanting seedlings, water them first. Then, you can use a spoon or similar small instrument to carefully lift the seedling, including its roots, out of the tray. Again, handle the seedling by the root ball, not the stem or leaves.