How interesting this all is! Yesterday (day 14 from first hatching) the mother started construction on her next nest in the other bamboo planter in our courtyard. I heard her fly in, so stopped to watch what I thought would be her hunting for insects for the babies. Instead, she landed on a branch and I saw her doing something that looked like preening her belly, but she came up with fluff in her beak and started jabbing it into a clump of something on the branch. I quickly realized