The Mysterious Cardinals

Two of our cardinals began building a nest in a corner of the back porch the first weekend in May. Mrs Cardie started sitting on the nest shortly thereafter; by Wednesday she was firmly ensconced. We began keeping a close eye on the cats and trying to keep them in as much as possible. The nest is just outside the French doors that lead from our bedroom to the back yard.
The following Sunday night, I couldn't sleep, and so turned on the light and read for a while. Hamilton was very fussy and I thought, what harm can he do in the middle of the night? The birds are all asleep... So I let him out. Within 3 minutes I heard a sound and leaped up and ran outside just in time to pluck him from 3/4 of the way up the cedar post at the top of which sits the nest. (And he is so giant that when he is stretched out, as when climbing, he's a good 3 feet long, or so it seems, like a small jungle cat.)
Apparently I was very middle-of-the-night loopy, because before too long, Fritz (aka Mr Loud) was being, yes, LOUD, and I thought, what harm can he do in the middle of the night? The birds are all asleep... and not 3 minutes later I heard a sound and leaped up and ran outside just in time to pluck him out of the roof of the porch, off the very beam which sits atop the cedar post at the top of which sits the nest. I always think of Fritz as the lesser killer of the two boy cats, but he knew what he was going for that night. So this is what led to the no-cats-out-till-the-babies-are-hatched-and-fledged rule.
We kept them in for over 2 weeks. It was hell. Mr Loud is called that for a reason. We went out of town for three days; our friend who animal-sat slept in the living room after the first night. We came back on Tuesday, 2 weeks after the initial nest-sitting began, and the next day or so, I was thrilled to see Mr & Mrs Cardie coming to the nest with food! They were feeding the babies! We watched their uneventful comings and goings till Friday. That morning, I saw a scrub jay very close to the nest, while Mrs C looked on alarmedly from afar; I opened the door and hissed it away, It left, only to be replaced by a titmouse, also looking very interested, and I hissed it away, too. But after that, we didn't see either parent at the nest again. It was too early, we thought, for the babies to have fledged, but on the other hand, maybe the eggs were laid sooner than we thought, or maybe they abandoned the babies, or maybe there never were any babies, or maybe the eggs got eaten by snakes, but I had seen the parents with food, so what happened?
Finally, this Saturday, after a full day of no more Mrs, Hugh took pictures of the inside of the nest. Thankfully there were no dead babies in it. There were no eggshell shards either. What happened? Were the babies ever there at all? Could they have left without us seeing them? Last year there were bird babies everywhere; this year, not so many.
I did see Mr C at the birdfeeder the other day. He took a sunflower seed away to someone in the tree, but I couldn't see if it was a baby or if it was Mrs C being shy. I am waiting, I am waiting, for our cardinal baby...