To our Zoological Park visitors the African weaver birds are a wonder and a delight. Orioles and caciques do not build nests in captivity, but the weavers blithely transfer their activities to their spacious cage in our tropical-bird house. The bird-men keep them supplied with raffia grass, and they do the rest. Fortunately for us, they weave nests for fun, and work at it all the year round! Millions of visitors have watched them doing it. To facilitate their work the upper half of their cage is judiciously supplied with tree-branches of the proper size and architectural slant. The weaving covers many horizontal branches. Sometimes a group of nests will be tied together in a structure four feet long; and it branches up, or down, or across, seemingly without rhyme or reason. Some of the weavers, which inhabit Africa, Malayana and Australia, are "communal" nest-builders. They build colonies of nests, close together. Imagine twenty-five or more Baltimore orioles massing their nests together on one side of a single tree, in a genuine village. That is the habit of some of the weaver birds;--and this brings us to what is called the most wonderful of all manifestations of house-building intelligence among birds. It is the community house of the little sociable weaver-bird of South Africa (_Philetoerus socius_). Having missed seeing the work of this species save in museums, I will quote from the Royal Natural History, written by the late Dr. Richard Lydekker, an excellent description: --This species congregates in large flocks, many pairs incubating their eggs under the same roof, which is composed of cartloads of grass piled on a branch of some camel- thorn tree in one enormous mass of an irregular umbrella shape, looking like a miniature haystack and almost solid, but with the under surface (which is nearly flat) honeycombed all over with little cavities, which serve not only as places for incubation, but also as a refuge against rain and wind. "They are constantly being repaired by their active little inhabitants. It is curious that even the initiated eye is constantly being deceived by these dome-topped structures, since at a distance they closely resemble native huts. The nesting- chambers themselves are warmly lined with feathers." Here must we abruptly end our exhibits of the intelligence of a few humble little birds as fairly representative of the wonderful mental ability and mechanical skill so common in the ranks of the birds of the world. It would be quite easy to write a volume on The Architectural Skill of Birds!