This is how I tap Birch Trees (in March) using a low-impact method, trying to minimise the amount of tools needed and potential damage to the tree. In most of Britain its only suitable to tap Birch trees in the first few weeks of March, however your local climate does effect when exactly the sap is rising, for example in Scottland it is later because of the colder weather, so do some research before collecting in your area. Admitedly this method can be a little tricky as the sap wants to naturally flow down the tree as appose your tap, but then again I cant really compare it against using a drill and boring a larger hole as I haven't yet tried using a drill.