Empty nests?

I am getting a lot of emails telling me that there is something wrong on a nest, or that the birds are gone. When I visit those nests, I find they are incubating, very low in the nest. Sometimes they are very hard to see...I watch for a little movement between the sticks, a little flutter of a feather. Sometimes no head pops up...it's cold and it been raining a lot and they really can hunker down.
I also visited some nests I had not been to in about nine days. One nest, that was empty on that last visit, had a pair present that were incubating. I followed the male to a perch and read his band...hmmmm, he was on a totally different nest 9 days ago. He had been seen there several times, copulating with the female. So I go to the nest where I had seen him before...female incubating there also, but I could not find a male anywhere. It started to rain so I will have to return and find the male to ID him. Musical nests. I wonder about the paternity there! I just can't catch up this year, with all the nests, all the bands to read, all the mate swapping and nest swapping. And I have another job too...gotta earn some money to pay for all this gas!