Guest blogger Matthew Carroll, a member of the RSPB’s conservation science team, tells us about a project he's working on investigating the impacts of climate change on the breeding success of threatened seabird species including kittiwakes.
We know much about how climate change is impacting wildlife and ecosystems. Many of the best-studied examples come from terrestrial systems, but some of the earliest and most dramatic impacts are happening in our oceans. Sea temperatures, salinity, water density and acidity are all changing. Species are moving towards the poles, plankton is blooming earlier, coral reefs are bleaching and dissolving, and fish communities are changing. And of course, the charismatic and important seabirds and sea mammals at the top of the food chain could also be affected.
Kittiwakes are one of our best-loved seabird species, but research has suggested that climate change is making it harder for them to raise chicks. The outcome of this has been big population declines in some areas of the UK. But rather than climate change directly affecting the birds, it’s believed that it might actually be affecting their food supply.
In many areas, kittiwakes rely heavily on small fish called sandeels for food during the breeding season. Higher temperatures seem to cause sandeel numbers to fall, so as things get warmer, there is less food to feed chicks with. So, big population declines might ultimately be caused by rising temperatures. If this is the case, further climate change could be catastrophic for kittiwakes, and perhaps even for other seabirds and sea mammals.
Image copyright: Genevieve Leaper (rspb-images.com)
Although this seems like a clear-cut case of the damaging effects of climate change, some important questions still need to be answered. Is temperature the only driver of declines, or are other changes to the ocean environment also important? Are different colonies throughout the country affected in the same way? And previously, researchers haven’t known exactly where birds are going out at sea; if conditions around food supplies are important, we need to know where the birds have been foraging! My role at the RSPB Centre for Conservation Science is to address some of these issues.
We’re very lucky to have access to data from the incredible FAME and STAR seabird tracking projects. Using these massive datasets, we can look at where kittiwakes have been foraging during the breeding season. Importantly, this means we can look at several colonies spread throughout the UK, and we know exactly which bits of sea to look at for each colony. The next step is to link changes in these foraging areas to population changes observed back at the colonies.
In doing this, I’ve been able to move on from just thinking about sea surface temperature, so that we can consider new aspects of the physical environment. To do this, I’ve had to dive into the world of 3-dimensional oceanography – as a climate change ecologist by training, this is not something I thought I’d ever have to do! But by considering this extra complexity, we hope to really get to the bottom of the mechanisms driving declines, and start to understand differences between different regions of the UK. After this, the next step is to use climate change projections to see what the future might hold for the UK’s kittiwakes.
The research is ongoing, so I can’t give any definitive answers yet, but early results are fairly exciting. When I can say more, I’ll be sure to report results here! When it comes to climate change impacts on wildlife, things can seem a bit bleak. But, if we can understand the mechanisms behind impacts, and where populations are most or least at risk, we may just be able to do something to ensure that our important wildlife populations are robust and resilient to the continuing effects of climate change.
Have you been lucky enough to see Kittiwakes? They'll shortly be arriving back at the colonies if they're not already so maybe a trip to add to your wishlist this year. Here are some RSPB reserves where you might chose to see them.
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