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The Wetland Bird Survey (WeBS) - Alerts

Abberton Reservoir

Data evaluated: winters 1974/75 to 1999/2000 inclusive
(New evaluation due: March 2006 to include additional data to winter 2004/05)

11 Evaluated Species: Great Crested Grebe, Cormorant, Wigeon, Gadwall, Teal, Pintail, Shoveler, Pochard, Tufted Duck, Goldeneye, Coot

3 Species Not Evaluated: Black-tailed Godwit¹, Golden Plover², Lapwing²
¹Data unsuitable for assessment of trends because sufficiently high numbers do not occur at this site or do so too infrequently to allow a meaningful interpretation under the WeBS Alerts methodology.
²This report is based on data previously prepared to generate WeBS national annual indices. Historically these species have not been included. Once the current phase of development of the WeBS integrated waterbird database has been completed it will be possible to assess site Alert status for these species.

High Alert:

Wigeon^10,25, Pintail¹⁰, Coot¹⁰

Medium Alert:
Shoveler¹⁰, Tufted Duck^10,25, Coot^All

The Abberton Reservoir SPA also supports nationally important numbers of Golden Plover in winter and Lapwing is included in the waterbird assemblage (Stroud et al. 2001). However, these two species are not included in the WeBS Alerts system.

Summary:

The numbers of five of the 11 evaluated species, including one occurring at internationally important numbers, have shown declines and there is thus cause for concern at the site, especially as these trends tend not to reflect trends at the regional or national level.

Declines in the numbers of Shoveler give particular cause for concern given its conservation status on the site.

There have also been recent declines in the numbers of the two other species which occur at the site in internationally important numbers, Gadwall and Teal, but because of the demographic properties of these species, Alerts have not been triggered. However, given the declines in the other species evaluated these declines may be real.

No direct adverse factors have been identified from the literature consulted for the Abberton Reservoir SPA.

Site trend

National trend (GB)

Regional trend (Anglian)

Increasing
or stable

Decreasing

Increasing
or decreasing

Decreasing

Short-
term Increasing
or stable GG, CA, WN, GA, T., PT, SV, PO, TU, GN, CO GG, CA, WN, GA, T., PT, SV, PO, TU, GN, CO

Decreasing

Medium-
term Increasing
or stable GG, CA, T., GA, PO, GN GG, CA, T., GA, PO, GN

Decreasing WN, SV, TU, CO, PT WN, SV, TU, CO, PT

Long-
term Increasing
or stable GG, CA, GA, T., PT, SV, GN PO GG, CA, GA, T., PT, SV, PO, GN

Decreasing WN, TU, CO WN, TU, CO

Detailed Account:

Click here for the complete account for Abberton that includes additional information (*pdf 675 kb)

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Throughout this site account the selection stage at which this SPA was cited for a given species (Stroud et al. 2001) is indicated: species names in normal, bold and italicised type corresponding to selection stage 1.1, 1.2 and 1.3 respectively.

Trends have been assessed over the short-, medium-, and long-terms (5, 10 and up to 25 years respectively). Where data have been collected for less than 25 years (see Methods) the maximum number of years available are used for calculating long-term alerts (specific details are available within the detailed account).

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