e-Digest Statistics about: Wildlife
Mammals
National monitoring schemes for wildlife are carried out by a wide range of organisations, often with the help of thousands of amateur and professional naturalists. The following paragraphs cover a selection of available data but these are illustrative only and not representative of all species and schemes in the UK.
A Review of British Mammals [6] was completed in 1995 for JNCC. The review gave, for the first time, broad estimates of the populations of all native and introduced mammals that are known to have bred in GB in the last thirty years, excluding cetaceans (i.e. whales, dolphins and porpoises). Estimates were also made of the geographical distribution and population trends of each species. Table 5 and Table 6 give summary information for the 63 species currently believed to be breeding in GB. Table 5 breaks down population change data between native and non-native species. Non-native species consist of 21 introduced or feral species which have had persistent breeding populations in the wild for at least fifteen years (for example the rabbit, grey squirrel, American mink and Chinese muntjac) and one migrant species (Nathusius' pipistrelle bat). More detailed information giving estimated populations, ranges and trends for individual species is shown in Table 7.
The population estimates are for numbers of mammals at the beginning of the breeding season and should be viewed as only the first stage in a process of estimating population sizes of British mammals and of monitoring population changes and trends. There are very few species for which an estimate of the actual population size is available; for most species the population size was calculated by the researchers either by estimating abundance relative to other species, or by multiplying the amount of suitable habitat by estimated population densities for those habitats. An assessment of the reliability of the population estimates for each species is given in Table 7.
For most species the assessments of population change over the last 30 years were based by the authors of the Review [6] on subjective criteria because there are very few species for which there are long-term population data. The species known or believed to be increasing in numbers include several which are already (or potentially) damaging to agriculture or silviculture, such as the rabbit, red deer, sika deer, roe deer and muntjac. They also include several species of conservation concern that had previously been reduced to low levels, for example, the polecat and otter (see also Table 9).
In Detail:
Wildlife monitoring (Environmental Change Network)
Further Information:
- Source:
- JNCC, Environment Agency
- Key Facts:
- Scarce and threatened native species
Data Tables:
| Table
No. |
Title | Download
file type |
| 5 | Estimated populations, geographic distribution and changes for mammals over the last 30 years, by taxonomic Order/Family | |
| 6 | Estimated changes in population or range of native and non-native mammals over the last 30 years | |
| 7 | Estimated populations, geographic distribution and changes for mammals over the last 30 years, by species | |
| 9 |
National otter surveys: 1977-79, 1984-86 and 1991-94 and 2000-02 |
|
| Related Table(s) from ECN section | ||
| 22 | Bat and bird monitoring at ECN terrestrial sites, Great Britain |
- References, further reading and links to other resources:
- [6] Harris, S., Morris, P., Wray, S. and Yalden, D., (1995). A Review of British Mammals. JNCC, Peterborough.
- Environment Agency: Otter Survey: 2000-2002
- Internet Links:
- Joint Nature Conservation Committee (JNCC)
- Environment Agency
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Page last modified: 16 September 2003
Page published: 10 September 2003