In order to find out how many eggs a Skua would lay, I marked some nests, and took the eggs as they were laid. In each case a second egg was laid, but when this was taken no more appeared. In two nests I removed the first egg as soon as it was laid, but left the second, which was then sat upon by the parent, who was content with it, or unable to lay a third. When any of us approached their nests the old birds would fly round in wide circles, making wild "stoops" at our heads each time they passed over us, in the evident attempt to frighten us away. Occasionally they would actually knock our heads with a wing, and nothing seeming to scare them off, they would swoop past us time after time in a most disconcerting manner. In order to keep them at a distance without having to keep a constant look-out, when I was in the neighbourhood of their nest, I used to walk about holding a ski-stick or the handle of my ice-axe straight above me, and they would swoop at the top of this instead of my head, which was infinitely preferable. One day when a high wind was blowing on top of Cape Adare, I had my ice-axe knocked clean out of my hand by one of the Skuas flying straight into the handle, the heavy blow seeming to affect the bird but slightly. There was a "skuary" on the screes, close to a thickly populated part of the rookery, but the majority of these birds made their nests right at the top of Cape Adare, from which point of vantage they surveyed the entire rookery, and a very sharp look-out they kept too, for no sooner did we start to flense a seal than a flock of them descended to gobble at the lumps of blubber as we threw them on the ground. In this occupation they exhibited the greatest jealousy, and when there was a hundred times as much blubber on the ground as all the skuas possibly could have eaten, they continually tried to drive each other away. When fighting they rarely stayed on the ground, but leapt at one another into the air, and one of the illustrations shows two Skuas in the act of doing this. Their great spread of wing is well shown in this photograph. (Fig. 71.) When penguins' eggs were plentiful in the rookery the Skuas flew very low over the ground, and as they passed over each colony of nests the sitting birds would crouch low upon them, a very necessary precaution, as I have described already in these pages the unerring way in which the Skuas picked up the penguins' eggs when they were left uncovered. Broken and empty shells strewed the ground in the vicinity of the Skuas' nests, and it is probable that in a large rookery, such as that at Cape Adare, thousands of eggs are destroyed by them annually.