Population trends of Little and Sandwich Terns sterna albifrons and S. sandvicensis in Britain and Ireland from 1969 to 1998
Atlantic seabirds , Volume 2 - Issue 3/4 p. 211- 226
Population trends of Little Terns Sterna albifrons and Sandwich Terns S. sandvicensis were determined between 1969 and 1998 using counts from sample colonies throughout the UK and Ireland. The Sandwich Tern population increased from c. 12 000 pairs in 1969 to c. 17 000 pairs in 1971, but then fell to c. 13 000 pairs in 1974. It then recovered at a rate of 6% per annum to c. 17 000 pairs in 1979 and fluctuated around 16 000 pairs until 1992. There was a second large population decline of 20% between 1992 and 1995, resulting in a total of c. 13 000 pairs in 1995. This decline appears to have halted up to 1998, when population size remained relatively stable at 13 500-14 000 pairs. The Little Tern population increased from 2000 pairs in 1969 to 2600 pairs in 1971 and then decreased to c. 1800 pairs in 1973. It increased again to a peak of 2800 in 1975 but then entered a longterm decline at an average rate of 1.23% per annum, punctuated by increases in 1988 and 1996. The population of c. 1700 in 1998 was the lowest recorded during the 30 year study and represents a 39% decline compared with 1975. The decline in Sandwich Tern populations appears to be confined primarily to the North Sea, with decreases being associated with events at individual colonies rather than at all colonies within the area. The declines in Little Tern populations appear to have occurred throughout the species range and are probably symptomatic of a chronic, widespread problem. Possible reasons for the declines in these populations are discussed and recommendations are made for further research, monitoring and conservation measures.
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Norman Ratcliffe, Georgina Pickerell, & Emma Brindley. (2000). Population trends of Little and Sandwich Terns sterna albifrons and S. sandvicensis in Britain and Ireland from 1969 to 1998. Atlantic seabirds, 2(3/4), 211–226.
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