Common Terns v large gulls

two of our pairs of Common Terns have young on a raft that is in a pit that at present is being used as a wash and brush up emporium by a few thousand large immature gulls every day -- this has not stopped the terns hatching 4 chicks between them but every large gull that passes over the raft receives a good mobbing -- LBB Gulls are sorted out for the greatest intensity of attack --- I had ben hoping to try and capture the chases but the only relatively close location is in a well located hide that strangely faces south, presumably so sun gazers can watch the sun all day long -- the slots are about 6 inches deep so you cannot even get a 500mm lens through them (resorted to 300) and of course reeds are rapidly growing over the slots to prevent you seeing anything but otherwise its a superb hide -- So I failed to get the shots I wanted but here are a few showing the intensity of the chase -- one shot shows that the tern actually sticks its bill into the back of the gull and I have other shots showing the terns pecking the undersides of the gulls -- no wonder they squark loudly and tens to avoid the raft after one attack--