Internationally important
numbers
A wetland is considered to be internationally important if it
regularly holds at least 1% of the individuals in a population of one species or
subspecies of waterbird.
Nationally important
numbers
A wetland in Britain is considered to be nationally important if it
regularly holds 1% or more of the estimated British population of one species or
subspecies of waterbird.
Sites of Special Scientific Interest (SSSI)
Areas notified under the Wildlife and Countryside Act 1981 for their
"special interest by reason of any of its flora, fauna, or geological or
physiographical features". They are the main statuary national conservation
designation to protect sites of nature conservation importance. These sites have
recently been given greater protection under the Countryside and Rights of Way
Act 2000.