My male zebra finch is raising his 2 babies since mom sadly passed away just after the chicks hatched. He is very attentive and has been taking good care of them.

Today, at day 21, both babies fledged. They were flying and perching pretty well, explored for about 2 hours, and then they both returned in the nest, and have not moved since then (it has been a couple of hours ago). Is this normal? Should I remove the nest?

Dad is feeding them in there and tries to call them back out. The babies are moving around in the nest, looking out, but are not coming out.

thank you for your advises!