The Common Wild Duck is also liable to depart widely from her usual habit in the selection of a site for her nest, sometimes adopting a Crow's nest, and even the tower of a church, which latter has occasioned much speculation amongst naturalists as to how the parent bird managed to convey her progeny safely to water. The Fly-catcher is amongst the foremost of our eccentric birds in the choice of breeding quarters, its nest having been found in street lamps in different parts of the country, and in one instance on the head of a hoe hanging against the wall of a tool-house. The nest was removed whilst the hoe was being used, and, when replaced, the birds, instead of deserting it, resumed operations, and eventually reared their brood. Another very interesting curiosity of recent date occurred in the neighbourhood of Skegness, where a pair of Marsh Titmice selected a farmer's letter-box for incubation purposes, and although it was opened twice daily, and the materials with which the birds began to build were several times cleared away, they doggedly persisted in their efforts, and eventually succeeded in making a nest and depositing the usual number of eggs. One of the strangest cases of all, and I should think the most remarkable on well-authenticated record, recently occurred near Colchester, where a pair of Common Wrens built their nest inside the skeleton of a hooded crow, which had been brought to justice and hung up as a warning to other winged depredators. These odd positions and situations are evidently not chosen for purposes of concealment from man, at any rate; indeed, it is a question whether some of them are not adopted to secure the advantage his presence affords against the incursions of predatory birds and animals. And, on the other hand, if these seeming departures from instinct be admitted as due to reason, it seems strange that whilst some birds are capable of this, others exhibit what seems to human understanding profound stupidity. I have known birds vainly try to build in positions where it was impossible for a nest to rest, each piece of material falling to the ground, until sufficient had been collected for a great many nests; yet the bird kept on collecting sticks, moss, and grasses, until probably she was obliged to drop her eggs in the fields. This is not a solitary instance, nor only once attempted, for close observation proved that the same inexplicably vain effort was continued from year to year, but whether by the same birds or not it is of course impossible to say. Some birds show a remarkable love for the same situation, in which they nest year after year for an incredible length of time. The same place is known to have been used by falcons for about a century and a quarter, and likely to continue if the birds are not molested. Blue Titmice are known to have selected the same quarters over a hundred years in unbroken succession.