e-Digest Statistics about: Wildlife
Wildlife monitoring
Otters
The fourth national otter survey of England was carried out from January 2000 to February 2002 by the Environment Agency.
Otter surveys are carried out by surveyors examining 600m stretches of river for evidence of otter tracks or spraints/faeces. If evidence is found the stretch is counted as a 'positive survey'. Table 9 gives the results of major surveys undertaken in GB in 1977-79, 1984-86, 1991-94 and 2000-02 [10]. To enable comparisons to be made, these data in Table 9 cover only stretches of river which were surveyed in all three periods. The increase in 'positive surveys' between 1977-79 and 1991 is believed to reflect actual increases in the British otter population, but it is important to note that figures given in the table refer to the distribution of evidence of otters' presence and not to their population numbers.
The size of changes in the distribution should be viewed with some caution because of differences between surveyors and differences in weather conditions during and between surveys. Dry weather conditions are likely to increase the probability of finding evidence of otter presence, and although rivers are not surveyed while they are in flood, high water is likely to wash away some signs of otters.
In Detail:
- Wildlife monitoring (Environmental Change Network)
- Mammals
Further Information:
- Source:
- Environment Agency
Data Tables:
| Table
No. |
Title | Download
file type |
| 9 | National otter surveys: 1977-79, 1984-86, 1991-1994 and 2000-02, Great Britain |
- References, further reading and links to other resources:
- [10] The Vincent Wildlife Trust, (1993). Otter Survey of Wales (Arolwg ar Ddyfrgwn yng Nghymru), 1991. The Vincent Wildlife Trust, London.
- Internet Links:
- Environment Agency
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Page last modified: 16 September 2003
Page published: 10 September 2003