sadly they aren't, only the G crested....ring up english nature.,..or whatever its called now and seek advice...
just a warning a SSSI comes with some very strict rules and regulations. witch can make shooting and farming practices very hard if not impossball. have a look, all the rules can be found on the net. it may be more trouble than is worth depending what the land use / uses are. dont get me wrong we need to work with consavation as much as we can. but theres a lot we can do our selfs befor getting possibly anti field sport goverment bodies involved.