BIRD LIFE THROUGHOUT THE YEAR
tree in its prime. The sap which exudes from the mouths of the holes made by the goat-moth caterpillar is particularly attractive to many insects. Hornets may constantly be seen visiting the trees from which it exudes, while its fermenting sweetness acts as a bait to the stag-beetle and to many butterflies. Upon one occasion we noted that some alders much attacked by goat-moth had drawn no less than twenty-five red-admiral butterflies to the spot. All were in perfect condition and formed a brilliant picture. Few are the localities where one may now hope to watch the buoyant flight of the purple-emperor round the tops of the tallest oaks or the graceful evolutions of the white admiral. Some of our finer English butterflies seem to be dying out in a way which cannot be altogether accounted for by the large increase in the number of those who wield the net.
Teeming as they do with insect life, it will easily be understood why oak-woods are frequented by so many birds. Compare in this respect a grove of oaks, all alive with the songs and movements of birds, with the silent and deserted pine-wood. When the hornbeam grows intermixed with the oak, as at Epping and in many of the woodlands to the north of London, we shall find the shy Hawfinch, whose big conical bill is strong enough to crush a cherry stone. Nutshells firmly placed in crevices of the bark are sure token of the presence of the Nuthatch, which fixes them thus that