Who stole my marigolds?

I had planted marigolds from seed so I could plant them next to the tomatoes because I read it was a nice companion plant for them. It apparently keeps the bugs away. I had more than enough seedlings, so I put 4 of them in a hanging basket. I hung the hanging basket on one of the 4x4 post on the garden fence. But the other day, I went out to water the plants, and something had stolen all 4 of the seedlings out of the basket. What the &%$#@? Any ideas what could have taken / eaten this? I mean, the seedlings were 3 inches tall, as big as the 2nd photo below. It's so weird, it's literally suspended 4 feet in the air on the garden post. Do you think it was a bird or insect?
Luckily, I had more marigold seedlings so I replanted the hanging basket. This time however, I am going to try to outsmart whatever took my plants. I'm going to let these babies grow much larger before I hang them in the garden!