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Background
Despite involving only a relatively
small number of sites, estuaries collectively represent
the most important habitat for wintering waterbirds in
the UK. They are also inherently different from the
thousands of inland sites counted for WeBS. The influence
of the tide means that the birds have to be much more
mobile, both within and between sites. WeBS Core Counts
on estuaries have, in general, been based around high
tide roosts. Although important in themselves, roost
sites are usually secondary in importance to the manner
in which waterbirds make use of a site for feeding. Therefore,
information gathered about these sites at high tide
will only provide part of the picture. The WeBS Low
Tide Counts scheme, which was initiated in the winter
of 1992-93, aims to monitor, assess and regularly update
information on the relative importance of intertidal
feeding areas of UK estuaries for wintering waterbirds
and thus to complement the information gathered by WeBS
Core Counts on estuaries.
WeBS Low Tide Counts provide the crucial
information needed to assess the potential effects on
waterbird populations of a variety of human activities
which affect the extent or value of intertidal habitats,
such as dock developments, proposals for recreational
activities, tidal power barrages, marinas and housing
schemes. The data gathered contribute greatly to the
conservation of waterbirds by providing supporting information
for the establishment and management of the UK network
of Ramsar sites and Special Protection Areas (SPAs),
other site designations and whole estuary conservation
plans. In addition, WeBS Low Tide Counts enhance our
knowledge of the low water distribution of waterbirds
and provide the data that highlight regional variations
in habitat use. In particular, WeBS Low Tide Counts
should help us to understand, predict and possibly plan
for compensation for the effects of sea-level rise on
the UK’s internationally important estuarine waterbird
populations.
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Methods
The scheme provides information on
the numbers of waterbirds feeding on subdivisions of
the intertidal habitat within estuaries. Given the extra
work that Low Tide Counts entail, often to the same
counters that carry out the Core Counts, WeBS aims to
cover most individual estuaries about once every six
years, although on some sites more frequent counts are
made. Co-ordinated counts of feeding and roosting waterbirds
are made by volunteers each month between November and
February on pre-established subdivisions of the intertidal
habitat in the period two hours either side of low tide.
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Background 
