This host of predatory animals speedily brought about a decrease in the number of rabbits, but their work was not confined to rabbits, and soon game birds and other species were found to be diminishing. The stoat and the weasel are much more bloodthirsty than the ferret, and the widespread destruction is attributed to them rather than to the latter animal. Now that some of the native birds are threatened with extermination, it has been suggested to set aside an island along the New Zealand coast, where the more interesting indigenous species can be kept safe from their enemies and saved from complete extinction.
Birds are dependent on the elements as well as is man, and in the want of materials and the requirements in nest-building the birds are comparable to the lords of creation.
It is not a rare thing for a pair of robins to be badly handicapped in nesting-time by a lack of rain, for in May, and even in the showery month of April, there is occasionally a dry run of weather lasting for more than a week.
I have seen a pair of robins start a nest, and the dry weather would come on and stop operations, and the disconsolate pair would wait for the rain so that they could make mortar for their nest. Robins must have mud to use in the construction of their little home, and all the dry materials will avail them nothing unless there is a good stock of mortar on hand to cement the grass, rags, and other materials together.
On one occasion we supplied a pair of redbreasts with plenty of mortar by letting the hydrant run on the ground. The delighted robins immediately accepted the situation and gathered materials for the partially finished home, which was quickly completed and the four beautiful eggs deposited. We broke the law by letting the water run, but then we can excuse ourselves in behalf of the faithful birds by saying that "necessity knows no law."
The eave-swallows also require mortar for the construction of their nests, and they select quarters not very far removed from lakes, ponds, or streams. There is a neighborhood where the swallows used to build in great numbers, and the barns were well patronized by these little insect-feeders, rows of the gourd-shaped nests being seen beneath the eaves.