Conservation Science in the RSPB 2006

2
Willow warbler
Ben Hall (rspb-images.com
Introduction
Welcome to the fifth report on the
RSPB's scientific work. While the
score or more of projects included
in this report represents just a
snapshot of our overall scientific
programme, we hope they will
demonstrate the depth and
breadth of the RSPB’s scientific
work. A more complete list of our
scientific projects can be found in
last year's report, available at
www.rspb.org.uk/science.
Two of the projects included in this
report outline an emerging issue for
the RSPB, and indeed ornithologists
and conservation biologists more
generally – the decline of longdistance
migrant birds. The first
project, on pages 16–17, did not start
life as a study of migrants, rather it
was a re-survey of birds in more than
350 woods throughout Britain. This
large project (involving the RSPB,
BTO, Defra, EN – under the Action
for Birds in England, AfBiE,
partnership – FC and the Woodland
Trust) was set up amid concerns
about declines of woodland birds.
One of its more striking results,
however, was that all seven long
distance migrants surveyed in these
woods had declined over a period of
20 years or so, some dramatically so.
Woodland populations of, for
example, willow warbler, wood
warbler and tree pipit, all declined by
more than a half.
The second study, on pages 20–21,
adopted a much broader approach,
using data on population trends of all
breeding birds in most European
countries during 1970–2000, collated
by BirdLife for its recent publication
Birds in Europe. Analyses of these
data showed that inter-continental
migrants had declined more than
those that winter in Europe.
Interestingly, although some bird
species that breed in Europe migrate
to Asia, the declines of long-distance
migrants seem to be restricted to
those that winter in Africa.
While it is tempting to assume that
these declines are due to problems
on migration or wintering grounds,
this may not be the case, as
migrants may be struggling on their
breeding grounds for a range of
reasons. With funding from EN,
under AfBiE, we are reviewing the
evidence for these declines in order
to understand their causes better.
While we await this more complete
understanding, climate change is
strongly implicated in the decline of
the ring ouzel, one of UK’s rarer
migrant birds, albeit one that winters
in North Africa rather than crossing
the Sahara. A study, reported on
pages 37–38, involving the RSPB,
SNH, NERC, Scottish Ornithologists’
Club, Cambridge University and
several ouzel enthusiasts, has shown
that declines of ring ouzels in
southern Scotland were greatest in
years that followed warm summers,
and that recent changes in British
summer temperatures have been
large enough to account for this
species’ decline. We have recently
started a new project in Scotland to
understand why warmer
temperatures create problems
for ouzels.