Protective Association of Wasps and Caciques. The colonizing caciques, of South America, representing four genera, are very solicitous of the safety of their colonies. In numerous cases, these colonies are found in association with wasps, one or more nests invariably being found near the nests of the birds. It is natural to infer that this strange association is due to the initiative of the birds. When monkeys attack the birds, the birds need the stinging insects. As usual in the study of wild creatures, the first thing that we encounter in the wild bird is Temperament. On this hangs the success or failure of a species in association with man. Temperament in the most intellectual wild creatures is just as evident and negotiable to the human eye as colors are in fur or feathers. A vastly preponderating number of bird species are of sanguine temperament; and it is this fact alone that renders it possible for us to exhibit continuously from 700 to 800 species of birds. Sensible behavior in captivity is the one conspicuous trait of character in which birds mentally and physically are far better balanced than mammals. But few birds are foolishly nervous or hysterical, and when once settled down the great majority of them are sanguine and philosophical. Birds of a great many species can be caught in an adult state and settled down in captivity without difficulty; whereas all save a few species of mammals, when captured as adults, are irreconcilable fighters and many of them die far too quickly. In a well-regulated zoological park nearly every animal that has been caught when adult is a failure and a nuisance. To name the species of birds that can be caught fully grown and settled down for exhibition purposes, would create a list of formidable length. It is indeed fortunate for us that this is true; for the rearing of nestlings is a tedious task. A conspicuous exception to the rule of philosophic sedateness in newly caught birds is the loon, or great northern diver. That bird is so exceedingly nervous and foolish, and so persistent in its evil ways, that never once have we succeeded in inducing a loon to settle down on exhibition and be good. When caught and placed in our kind of captivity, the loon goes daft. It dives and dives, and swims under water until it is completely exhausted; it loses its appetite, and very soon dies. Of course if one had a whole marine biological station to place at the disposal of the foolish loon, it might get on. There are other odd exceptions to the rule of normal bird conduct. Some of our upland game birds, particularly the Franklin grouse and ptarmigan of the Rocky Mountains, display real mental deficiencies in the very necessary business of self-preservation.