Weaverbirds, Chapter 1

The only mention of weaverbirds in the text is as follows:

A colony of weaverbirds lived in a tree near his house, and he spent time watching them build and maintain their baglike nests. They say that one day near Christmas he carried a sick bird into his house, where it died, perhaps in his hands. The bird may have been a weaverbird— no one knows— and it may have died of a Level 4 virus— no one knows.