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Mid-season reports from RSPB coastal
reserves suggest that Scotland's seabirds are having yet
another poor breeding season, with some areas in the North
and West displaying near empty cliffs where there should
be thousands of birds nesting.
Climate change seems to be be disrupting food
availability, but more research is needed to better
understand changes in the the complex marine ecosystem.
Scotland's long and diverse coastline support's an
incredible 45% of the EU's breeding seabird population.
Although the full picture won't be known until later in
the summer, it's already clear that some areas have had a
disastrous year, with Orkney, parts of Shetland and the
North West suffering badly - definitely worse than last
year, and probably the worst since the dreadful 2004
season.
Other areas of the country - East coast reserves like
Fowlsheugh and Troup Head, and Southern colonies like Mull
of Galloway - seem to be holding up better, but in line
with recent years still down from historical highs. Even
in the South things might take a turn for the worse; large
chicks can still die if food becomes scarce.
The mixed fortunes between different species make the
changes harder to assess. Common terns seem to have done
consistently badly around the country, with kittiwakes
holding on in the South and East, but guillemots have once
again been hit hard.
Norman Ratcliffe, seabird ecologist with RSPB Scotland,
said: 'Yet again Scotland's seabirds seem to have had
another worrying season. Our reserves on Orkney and the
west coast definitely seem to have suffered from lack of
food to feed chicks. Some cliffs which should be packed
with birds are just about bare, as adult birds abandon the
nest once their breeding attempt has failed.
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'This is all linked to food availability, which can be
disrupted for a number of reasons. We're fairly certain
that on the East coast, rising sea temperatures are
leading to plankton regime shifts, which in turn affects
fish like sandeels - a major food source for seabirds.
'Sandeels might be abundant for a time but when this
critical food source enters the next phase of its life
cycle they swim down to the bottom of the sea and bury
themselves in the sand, meaning they become unavailable
as food. This often happens sometime in July, but if it
occurs early you can get mass mortality of near-fledged
chicks as has been seen for Coquet terns this year.
'Parent birds may then switch to pipefish, but chicks
find these hard to swallow, they are less nutritious,
and the parents spend much longer away from the nest
leaving chicks vulnerable to predation and attack from
neighbouring nests.'
In other parts of the country, the relationship between
temperature and food isn't as clear cut and requires
more research. It is not as simple as saying 'warmer
waters are bad for seabirds', because if warmer waters
bring more food then seabirds will do well. Puffins in
Norway do well in warmer years because herring there are
more productive in higher sea temperatures.
A full analysis of the season will only be possible at
the end of the summer, but RSPB believes it is indeed
very worrying that this is another in a recurrent run of
bad seabird breeding years in Scotland, and an
indication of how wildlife is having difficulty
adjusting to our changing climate. |
