Part 3

As a further illustration, let us take the eggs of the Golden and Green Plovers, and consider for a moment their size, shape, number, and colour.

All these qualities serve some well-defined and demonstrably useful end. Firstly, their size is abnormally large compared with that of the layer, but this is a provision which supplies the necessary size and strength of the young bird to enable it to cope with the surrounding conditions of its first days of self-feeding and locomotion amongst coarse grass and other obstacles.

Secondly, the shape of the egg serves to economise space, an important point where the eggs are large and the bird small. Thus the four pear-shaped eggs, having their small ends all pointing to a common centre, practically form a square, and thus enable the bird to cover them all at the same time.

Thirdly, the number of eggs is always four, and by such limitation the form of the square is preserved, and the difficulty of a small bird covering a number of large eggs satisfactorily surmounted. I have often disarranged the order of Plovers' eggs, but always found that the first thing done by the bird on her return was to reduce chaos to order by turning the round ends out and the small ones into the centre of her little household.

Lastly, we come to the beautiful harmony of colouring of the eggs with surrounding objects, rendering them often very difficult to find, even by a practised eye, and the scant nest still further aiding in the chances against discovery.

The Sandpiper affords an admirable instance of the assimilation of its eggs to surrounding objects, and the extreme difficulty experienced in finding them attests to its protective utility.

=Why Eggs Vary so much in Point of Number.=--The number of eggs laid by birds of different orders seems to be regulated by the danger to which they are exposed and the amount of food which the parents will be able to supply.

Thus, the Eagle in its inaccessible eyrie enjoys almost perfect immunity from danger, and has only two young ones, for which, however, the supply of food is only equal to the demand, and it is probable that one more voracious appetite would seriously endanger the safety of the whole family.

On the other hand, take the Common Partridge with its sixteen or twenty eggs, the high percentage of its dangers, and the generally abundant supply of food.

Again, the Swift, on its untiring wings for sixteen hours a day, avoids the majority of dangers which threaten less favoured birds, and only lays two eggs, in a position very few other birds could adopt, yet one which secures her little household the amount of safety necessary for the due survival of the species. However, with her limited family, dexterity on the wing, and enduring powers, she seems to have no leisure time during the period her young require feeding. As an opposite, take the House Sparrow, with its five or six eggs, innumerable dangers, and easy access to food, and it must be confessed these things are ordered by a power of infinite wisdom.

=Curious Nesting-Places.=--The general situation and locality in which each bird's nest is likely to be found are mentioned in dealing with the bird under its separate heading; however, it may not be uninteresting to chronicle a few of the most remarkable and well-authenticated departures from accepted rules.

I have myself found a Dipper's nest on the branch of a tree twelve or thirteen feet from the water and twenty from the bank. This nest was of ordinary shape and size, its material being of the same kind as others, and securely fastened amongst the prongs of the branch like a Missel Thrush's. When the parent bird was disturbed she dived into the pool below to make her escape (a habit invariably adopted when nesting in an ordinary position). She reared her young in safety, however, in spite of the awkward situation she had selected, and I have every reason to believe got them off without mishap. I have also found a Thrush's nest on the ground, precisely in the position a Lark selects.

House Sparrows furnish many examples of curious situations adopted for incubatory purposes. Not long ago a pair of these birds built their nest, and successfully hatched a brood, in the cartridge-box of a cannon which was fired twice daily in the Gun Park at Woolwich. It is a notable fact that in some parts of the country Sparrows build extensively in trees, whilst in others such a circumstance is unknown. Some ornithologists are of opinion that it is an hereditary habit, others supposing that it is resorted to for the sake of coolness in hot weather; but a reason I incline to is that in parts of the country where houses and out-buildings are made of stone the birds find ample accommodation in joints, crevices, and crannies where the mortar has been dislodged, and are therefore not driven to the necessity of adopting trees, like birds found in districts where the houses are made of bricks, consequently closer, and affording less opportunity for nest-building. This bird, besides its noted pugnacity, is an arrant rogue, and invariably takes advantage of the House Martin's labour. I have known a house with twenty nests all close together under its eaves, about half of which were occupied by Sparrows, which had, in some cases where the nests were new, been actually watched ejecting the eggs of the original owners.

The Robin is noted for its caprice in the selection of a nesting site, and has been found hatching its eggs in nearly every conceivable situation, from the ordinary mossy bank to the pocket of a gardener's old coat which had been hanging undisturbed for several weeks in a tool-house. Old kettles, water-cans, inverted plant pots, &c., in buildings close to machinery in daily motion, and other equally curious places, are by no means rare occurrences. A case is recorded of a Robin's nest having been built in the hole made by a cannon-ball through the mizzen-mast against which Lord Nelson was standing when he received his death-wound on board the Victory.

Swallows have also been known to adopt quite foreign situations for breeding purposes, such as holes in trees, and even openly on the branches.

Cases are known of the Starling building its nest down holes in the earth, and also quite exposed in trees, similar to the nest of the Sparrow. It has also been found going shares with a Magpie.

The Pied Wagtail occasionally chooses strange quarters, one case being on record of a pair building beneath a railway switch, over which trains passed nearly every hour in the day within a few inches of the nest.

The roof of a house in Hull was once selected by two pairs of Rooks for nidification, and proved a successful choice, for they managed to build nests and rear their young.

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.

=On Forming a Collection.=--My concluding remarks will be devoted to the guidance of such as require to make a collection of eggs.

Keep close watch on the building operations of the birds whose eggs are required. Dippers, Thrushes, and many others commence early in the spring, especially after a mild winter.

Take only one specimen, and not until you have reason to believe the bird has done laying. Never under any circumstances take an egg when you have ground to suppose incubation has commenced, or is in an advanced stage, for besides the cruelty of the thing, it will often be of no use.

The specimen being secured, it is taken for granted the collector is furnished with the necessary drill and blow-pipe, procurable at any naturalist's shop. The next proceeding is to drill a small hole exactly on the side of the egg, selecting that of a spotted one with the least characteristic marks on it. Then insert the end of the blow-pipe, or rather direct the current of air sent through it into the hole made, being careful with small eggs not to burst them, or squeeze them until they collapse under the pressure of the fingers. When the contents have been emptied wash the egg out with clean water, introduced through the blow-pipe, being careful not to wet the outside more than necessary, or rub it too much, as the beautiful colouring of many eggs is easily displaced. When the egg has been blown, and properly dried inside and out, an operation needing some care, the hole should be covered over with a neat piece of gummed paper, on which the name of the specimen may be written, this being found especially useful when eggs of different kinds get mixed.