CREATURE FEATURE - GUILLEMOTS
Guillemots (the black and white birds towards the top of the cliff) make no nest - they simply lay their eggs directly onto the narrow rock ledges. A parent bird keeps the single egg warm by holding it on top of its feet, covered by its belly feathers. Their eggs are long and pointed at one end, which makes them less likely to roll off the cliff. The eggs also have different markings, which may help the parent bird to recognise its own eggs amongst thousands of others on the ledges. Imagine trying to find your egg amongst the others on a cliff like this!
Guillemot chicks leave the ledges for the sea with a parent or other adult bird after only 18 days, when they are still only a third grown and unable to fly. This means that the parent birds no longer have to fly from the sea surface up to the breeding cliffs to feed their young - a great effort for a bird which has small wings and is not a strong flier. Why then do they have such small wings? Guillemots and razorbills have wings adapted for underwater swimming. They duck from the sea surface and 'fly' underwater, chasing sandeels and other small fish for food. Razorbills can dive to 120 metres, but guillemots can dive to at least 180 metres.
In late summer, adult auks moult their feathers at sea and so become flightless, like their chicks. At this flightless stage the birds are particularly vulnerable to oil spills because they cannot fly away from them. They can also become exhausted and be driven ashore by strong onshore winds.