Ground nesting Fulmars on North Ronaldsay

On of the features of our visit to North Ronaldsay today was the ground nesting fulmars. All along the drystone walls near the sea and even occasionally just on the grass right out in the open there were fulmar nests. I don't think I've ever seen anything like it before. Occasionally you'd be walking along looking out to sea and you'd inadvertently walk within inches of a nest, much to the chagrin of the occupier. I guess that the reason they nest like this is of the lack of cliff habitat available, but just as importantly the lack of predators on the island.