Mike Hamilton photographed a pair of Bushtits building their sock-like, hanging nest. Both the male and the female work in building the pendulous nest, made from moss, lichen, and spider webs. The female (she's the one with yellow eyes) focuses more on the bowl, while the male builds out the interior. From the start of nest building to the laying of the first egg is about a month.
The female usually lays six eggs, and both sexes incubate. The pair may raise two broods in a season.
Bushtits are rare in that some pairs have helpers (scientists call them "supernumeraries"), which, even more unusually, can be adult males. These adults, after failing in their own breeding attempts or simply not breeding, may assist in incubation and feeding of the young in successful nests. The nest also serves as a night roost for adults -- both parents and helpers.
Amazing, isn't it, that such an incredible structure is used for only one season!
All photos © Mike Hamilton. Thanks, Mike!