Enemies of the water-vole—The heron—The death-stroke—Ways of the heron—Watching for fish—A hint to naturalists—Observers in the New Forest—Return to wild habits—The fox, the cow, and the owl—The heron and the eel—The cormorant and the conger—The heron’s power of wing—How the heron settles—Its resting-place—Power of the heron’s beak—Heronry in Wanstead Park. The water-vole has but few enemies whom it need fear, and one of them is now so scarce that the animal enjoys a practical immunity from it. This is the heron (_Ardea cinerea_), which has suffered great diminution of its numbers since the spread of agriculture. Even now, however, when the brook is far away from the habitations of man, the heron may be detected by a sharp eye standing motionless in the stream, and looking out for prey. Being as still as if cut out of stone, neither fish nor water-vole sees it, and if the latter should happen to approach within striking distance, it will be instantly killed by a sharp stroke on the back of the head. The throat of the heron looks too small to allow the bird to swallow any animal larger than a very small mouse; but it is so dilatable that the largest water-vole can be swallowed with perfect ease. The bird, in fact, is not at all fastidious about its food, and will eat fish, frogs, toads, or water-voles with perfect impartiality. It has even been known to devour young waterhens, swimming out to their nest, and snatching up the unsuspecting brood. In fact, all is fish that comes to its beak. If the reader should be fortunate enough to espy a heron while watching for prey, let him make the most of the opportunity. Although the heron is a large bird, it is not easily seen. In the first place, there are few birds which present so many different aspects. When it stalks over the ground with erect bearing and alert gestures it seems as conspicuous a bird as can well be imagined. Still more conspicuous does it appear when flying, the ample wings spread, the head and neck stretched forwards, and the long legs extending backwards by way of balance. But when it is on the look-out for the easily-startled fish it must remain absolutely still. So it stands as motionless as a stuffed bird, its long neck sunk and hidden among the feathers of the shoulders, and nothing but the glancing eye denoting that it is alive.