Kevin Slagboom asked about Violet-green Swallows abandoning
nests if the nests have been disturbed. From what I understand,
once eggs are being incubated, most birds will try to tough it out,
and would be more likely to stay if they do not detect missing eggs.

I know many bird rehabilitators make a point of returning baby birds
to the nests they fell from whenever possible, or even to foster nests
of the same species. (There's some question in my mind about
how well they monitor the results of this and whether it doesn't
sometimes backfire.)

Since we just had our Loon Festival here, I've been hearing lots
of discussion of loons being disturbed and failing to nest
successfully. Either they are very skittish and prone to abandon
eggs and even chicks, or the situation is more complex than that
and still not well understood. At any rate, lakes tend to lose
their loons as civilization encroaches and it's heck getting them
back again.

Chris Maack
Anchorage (still slightly loony) AK
CMaack at compuserve.com