The blue light was coming from multiple beasts. They were all different forms of water elemental beasts that had similar bodies. Some were in the shapes of birds while others mimicked butterflies and other insects. They were using their abilities to move through the forest around capturing the starlight and releasing blue glows.
"The beasts here are fairly peaceful as long as you are respectful. Because the water fairies here are some of the strongest young beasts, they have the chance to grow in to alternate forms. Most are still weak because there is no need for them to become powerful offensive beasts." Doc enjoyed showing this side of beasts.
"They come out on clear nights like this to enjoy the cool air. They also like to filter the light through their water bodies. It's a sight that attracts each other and allows for the more unique water and spiritual type beasts to grow. Some of them will even merge with each other forming new beats."