In this pop-up, layers of branches create a forest around a mother and baby bird. I created a movable tab mechanism that is hidden behind the spread. When the tab is pulled, the mother bird leans down to feed the baby a worm. The tab is pushed back in, the mother stands back up and the word "Yum!" appears above the baby's head. The challenge here was figuring out how to reveal the word only when the tab moved upward. I carefully studied Andrew Baron's engineering in  by Paul Zelinsky to come up with a solution.