|MadSci Network: Zoology|
Jeez, when I signed up to answer "zoology" questions I never thought I'd be getting bird psychology questions! Since I am not a licensed bird psychologist I cannot legally make a diagnosis; this is the nineties after all and the last thing I need now is to be sued for emotional trauma by a nuthatch.
However, I do happen to know some legitimate ornithologists who spend large chunks out of the year actually going out and living amongst the gentle avifauna of our Global Village, so I put the question to them (they are real, honest-to-Gosh scientists, I swear) who tell me:
"...On the bird sitting on the dead chicks - it does sound a bit odd; birds will certainly continue to incubate eggs that are "dead" (they will even incubate wooden eggs - no comments now about brains) and others have been known to build new nests over old ones that contain eggs (usually in response to cowbird eggs). But brooding dead chicks . . . . who knows..."
"...I don't have a clue - although I suppose it depends on the experience of the mother. You are probably right that she may stick with it until the last egg is hatched [this was my own hypothesis], although there is undoubtedly a giving up time. It would be interesting to know if she is bringing in food for the dead babies. If they really are dead and she is bringing in food she is suffering from a deep case of denial!"
So there you have it. Personally, I believe the parenthetical comment in the former response about 'brains' is significant. Ethology (study of behavior) is a fascinating field; there are many things that simply don't have an answer (not surprising; I can't even account for my own behavior at times). And the behavior of mothers, in general, is in a peculiar class all by itself.
I realize this isn't a definitive answer, but it's as close as I can get. If you could find an expert bird ethologist you might get a better answer. Good luck, and hey, be supportive of the little lady!
Thanks for using MadSci Network!
Kelleen Flaherty, Washington University in Saint Louis
Try the links in the MadSci Library for more information on Zoology.