There is an argument that kittiwakes, and other cliff nesting seabirds, tolerate great black backed gulls nesting near them as they deter herring and lesser black backed gulls. If these latter two species were undeterred the predation rate would be much higher. During my period at this colony I witnessed the peripheral nest sites undergoing significant egg loss, but also the adults copulating again within 24 hours of loss. Some of the eggs loss was attributable to great black backed gulls, but not all. This is an hypothesis in need of testing.
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| Close up of egg predation |
Just a quick note: I was reviewing my blog and realized this is film of a Lesser Black-backed Gull predating eggs. There is an implication in the text that it is a Great Black-backed Gull - an error on my part for which I apologize. I am not certain why I made this mistake, but I did! At the time this was filmed a pair of Greats were certainly nesting near by, hence speculations about their role in reducing predation from other species, including the one in this image, were recalled and discussed. Looking back over a few years of work now I think there is no Great Black-backed Gull predation to speak of on this particular colony - but just south of it Greats most certainly predate Guillemot sites for eggs and chicks, and in passing attempt to do the same to Kittiwake nests. I think this is a more fertile hunting ground for them, due to spatial issues and nest density - in other words it is hard for a Great not to hit something when landing here! But we have yet to formally analyze all this.
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