Never mind (although feel free to contribute!). I went to the sialis site (should have done that first). They do indeed say that adults can be weakened following migration, that cold rainy weather can take a toll on them, and that bad weather can reduce the number of insects and the adults may starve to death particularly as they are weak from migration.

Very sad.

I'm hoping some of the others are just waiting till the weather improves a bit before getting serious about nesting.

I had a dead TRES in my box last year that I am sure was due to migration, not a mark on it. We have a cold snap right now and all of our TRES dissappeared and they all have nests two with eggs. Here in WI our TRES have been back since the end of March. It had been unusually warm for March and April and now it has turned a bit cooler. I did read they travel long distances to find food when the weather takes a turn for the worse.

Donna

There could be another reason the TRES died. Sometimes they can not get out of the box if it is a deep box. They do not have strength in their legs and sometimes become trapped. I take a small saw and cut a ladder in all of my boxes so the tres have something to grab on to when trying to get out of the box. This will help the babies too. I was at my neighbors last year and I saw a tres go into a box, but did not come out. We went out and sure enough...it couldn't get out cuz of the smooth surface below the entrance hold. Please cut grooves into the box...this will help. Sorry about your loss.

karen

Donna, our April was unseasonably warm also and the early migrants came as much as two weeks early. But then the last few days of April and beginning of May have been quite cold and migration seems to have come to a standstill. Usually we have orioles, r-b grosbeaks, and hummingbirds now, but not this year.

Karen, the boxes do have grooves and they have been used for eight years now with no birds being trapped inside. So although I understand that's a possibility, it seems unlikely to me unless this particular bird was especially weak.

Thank you both for the comments. It is sad. On the other hand, I have also lost a few birds recently because of nesting Cooper's hawks. I can't do anything about that. Life is just very hard in the wild.