Rose-Tu is expected to deliver a new elephant calf in the coming weeks. Her keepers are monitoring her blood-progesterone level. It will drop significantly when she's within a couple days of birth but they wish they had better, earlier indicators of when she'll go into labor. That’s why researchers have started documenting Rose-Tu's actions. They'll compare her actions to those of four other elephants.  Oregon Zoo Conservation Research Associate Karen Lewis says they'll also use data gathered during Rose-Tu's last pregnancy with Samudra (who, by the way, now weighs nearly two-tons.)