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SUMMARY OF BTO MONITORING REPORT ON WADER BIRD MONITORING IN
CARDIFF BAY.
The aim of the
monitoring study was to assess changes in the numbers, distribution
and survival of water birds in Cardiff Bay and surrounding areas
during construction of the Barrage and following impoundment.
The work has attempted to answer four main questions:
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Were the numbers and distribution of birds within the Bay
affected by construction work associated with the Barrage? |
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Were birds displaced by the Impoundment of the Bay and how
did the water bird community change? |
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Were birds displaced from the Bay able to re-locate to
other neighbouring sites? |
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Was there any impact on the condition and survival of birds
that were forced to re-locate? |
The study concentrated on 5 key species (that is, most
numerous) of over-wintering wader birds present in the Bay prior to
impoundment: Shelduck, Oystercatcher, Dunlin, Curlew and
Redshank.
Were the numbers and distribution of birds within the Bay affected
by construction work associated with the Barrage?
Initial
work indicated that the overall numbers of over-wintering water
birds supported in the Bay had declined prior to impoundment,
perhaps due to changes in habitat quality. The distribution
and behaviour of birds in the Bay were also affected by
disturbance caused by Barrage construction. |
Were birds displaced by the Impoundment of the Bay and how did the
water bird community change?
Prior to impoundment, the Bay supported a diverse water bird
community, dominated by large (over-wintering) numbers of
estuarine birds. Since impoundment a smaller community of
birds has existed in the Bay. Only very small numbers of the
5 key species (Shelduck, Oystercatcher, Dunlin, Curlew and
Redshank) have continued to use the Bay as a high tide roost site
during winter, and only occasionally do individuals remain to
forage at low tide. |
Were birds displaced from the Bay able to re-locate to other
neighbouring sites?
There
is evidence that 3 of the 5 key species (Shelduck, Oystercatcher
and Curlew) displaced from Cardiff Bay settled at adjacent sites
in the first winter following impoundment. However, these
increases were not maintained and, with the exception of Curlew,
there was no evidence that birds subsequently attempted to settle
elsewhere. In the case of Dunlin, it was not possible to
determine whether displaced birds were able to settle elsewhere
due to an ongoing decline of the local population. |
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Was there any impact on the condition and survival of birds that
were forced to re-locate?
Most of the Redshank from the Bay were displaced to the Rhymney
estuary. There is evidence that adult Redshank displaced
from the Bay had difficulty in maintaining their body condition in
the first winter following impoundment and suggested that the
winter survival rate of Cardiff Bay Redshank fell after their
displacement. |
The loss of the Bay as a habitat for over-wintering wader birds was
the subject of a compensation package agreed between the United
Kingdom Government and the European Community. This package
included the construction of the 1,000 acre Gwent Levels Wetlands
Reserve. These works were completed in 1999 and this Reserve is
now managed by the Countryside Council for Wales. |
