Nest sharing by two pair question

[twatripp]

New member here. I have searched the web everywhere and just haven't found the answer to a puzzle of House Finch behavior at my San Diego, CA area home. For several years - at least 7 - there have been two pair (I cannot believe it is the same two pair) that spend several months at my home. Every year they build a nest in the exact same corner on the beam supporting my covered deck. The two males and two females chase each other all around and then there are eggs -- normally three. What seems so odd to me is that all four birds seem to attend the eggs and then the babies. I have seen one male feed followed immediately by the other male. No sooner have the first brood fledged than there is another clutch of eggs.

As I sit here, looking out right now in late July, the four birds are sparring with each other. Since the wind knocked down the last nest, I appears that they are about to build another. This behavior has puzzled my wife and me for many years and have given us a lot of pleasure. But it sure seems odd to us and I hope somebody will let us know if it is unusual.

[finchmix22]

Finches some times do share incubating, nesting and feeding duties. It's lots of fun to watch their antics. Society's are the funniest and I think of them as the clowns of the finch world. Welcome to the forum!