Can animals de-spawn?

[Malicus]

While heading to my well, I saw a boar. My inventory was full, so I decided I'd kill it after I was done with what I was doing. However, I came back and simply could not find it, even after searching the forest quite a bit. Could it have just vanished?

[sami1337]

It probably hid behind a tree. Usually boars see me before i see them.

[Malicus]

I searched several times, and I couldn't find it, so... maybe it hid well. I eventually found a boar significantly further to the east, though I kind of doubt it was the same one.

[Lightning4]

I think creatures do despawn after a certain time in the world. They also seem to despawn in relation to time of day, if their animal type has that type of relation. Foxes seem most common during the day, while rats are exceptionally common during the night. Perhaps they even take the place of a pack of animals that were there during the day?