| Popis: |
The number of known sites (populations) documented by conservationists for the natterjack toad Bufo calamita between 1970 and 1990 in Britain rose from 21 to 40, excluding those resulting from translocations. The progressive reduction in rate of discovery of undocumented sites suggests that few further populations will be located. The real overall number of natterjack sites has probably changed little over this period, with successful translocations approximately compensating for the few (three to five) concurrent extinctions. More than 90% of matterjacks in Britain now live in the vicinity of just five river estuaries. Habitat protection, mainly the result of scheduling land as Sites of Special Scientific Interest (SSSI), has been increasingly effective in safeguarding natterjacks, the proportion of safeguarded sites rising from 60% in 1970 to 83% by 1990. However, the legislation for species protection has proved much less effective. Much of the recent damage on unscheduled sites was a result of agricultural improvements by landowners ignorant of the presence of natterjacks on their land. The breeding records from natterjack sites are used to examine the possible impacts of radioactivity and climate change, against which site protection alone is no safeguard. Recommendations are made for conserving natterjack populations in the future. |
