Why would they leave?

[Cjs180]

We had a pair of 2nd year birds here this year that came real late. In any event they built a nest and had 4 eggs. When we checked this past Wednesday 1 egg was gone. We haven’t seen the pair since last week. We still have visitors each day. We pulled the house down today and 1 of the 3 eggs was cracked so we removed it. You could clearly tell there was a bird in the egg. We put the other 2 eggs back.

The eggs should have hatched somewhere between last Wednesday and Friday. No sign of the parents anymore. Why would they just up and leave with 2 eggs left?

[brent]

That is interesting. I don't know the answer but I can share something that happened to me last year that was similar. I had a nest of 3. It was very late in the season and all of the other martins were gone. The parents stopped feeding the chicks. Maybe occasionally I would see a parent bring food and then it completely stopped. I tried to feed them but was hoping the parents would show up again. That didn't happen. I can only assume that the desire to migrate was stronger at that time. Or fear...something scared them. Or even, perhaps, they knew the chicks were not salvageable. I'd like to hear other responses. Heart breaking.
Brent

[flyin-lowe]

Usually the only reason a nesting pair would not complete the nesting cycle is because of a predator. I would guess either something got into the nest and got one or both of them (snake, owl, raccoon, etc.). It is possible something got one or both of them while they were out feeding but the odds of both being killed is a little low, and if one parent didn't return the other might stick around for a while anyway.
Do you have predator guards?

[Cjs180]

No owl guards. I do have tunnel entrances on our gourds and the SREH. We did have a real persistent SY male that was causing a lot of ruckus for about 3-4 days before they left. Possibly he caused a problem? But there was still 2 good eggs that were in the nest.

We do think we saw the male hanging around after the female left. But he was not around each day.

[C.C.Martins]

Cracked or pecked? May be too late to tell, however something happened to the female...male cannot incubate eggs. Either something got her while in there which caused a cracked egg, or she was out somewhere and got killed.

Please put up predator guards and snake netting.

[Cjs180]

Looked cracked.