Their courage, too, is extraordinary. The nest that is shown in the illustration is not in any of the usual sites that this gull selects, and is chosen for that reason, as showing the fearlessness of these birds, for it is built in a sheep-walk which the woolly folk had frequently to traverse, and was found out by the shepherd seeing all his flock, as they passed in single file, jumping at the same spot. On going to find the reason for this agility, the hen-bird was discovered sitting on her eggs. Of all the gulls, this is perhaps the least of a sea-bird. For it lives almost altogether on land, searching the beach and rocks for dead fish and other food cast up by the tide, and boldly coming inland to feed in ploughed lands, or follow the course of rivers, or pick up a living in harbours and docks, going back to the water to rest and sleep. Very different is the scene when the visitor, landing on one of their breeding-rocks or islands, disturbs the hosts of the lesser black-backed gulls, to that when he landed among the uncomplaining puffins. For the gulls resent the intrusion with wild cries and threats, and, instead of flying away, patiently disconsolate, to wait for the intruders' departure, wheel and whirl overhead, with angry clamour and noisy wings, making believe to swoop down on the trespassers, and shouting at them to go away. And they have good reason for their indignation, for their visitors carry off their eggs by the boat-load for sale among the hard-living islanders. [Illustration: AMONG THE SKUAS] But the black-back is a mischievous and predatory bird, doing infinite injury to more valuable species, like the eider-duck, whom it harries without remorse; and so one [Illustration: A COLONY OF CORMORANTS] can read of its eggs being cooked by the million without any keener feeling of regret than if they were apples. And, after all, the wholesale robbery of their nests does not reduce their myriads, for more than enough are hatched every year to fill the gaps caused by death. Being, too, so courageous, the gull escapes persecution by its larger companions, and even the sea-eagle prefers, with so large a choice of more timid victims, to leave such obstreperous birds alone. When threatened by the great bird of prey they join for the common defence, and the eagle is often seen, at long distances from the breeding-places, pursued by shouting gulls, and ignominiously mobbed out to sea. [Illustration: BLACK-THROATED DIVER]