According to National Geographic they are bioluminescent, but not sure how yet because in order to study live ones they are having to create little protective eyewear for them. Probably the cutest sentence in a scientific article I've read this decade. They use both bioluminescence and biofluorescence in the article.
https://news.nationalgeographic.com/2018/04/sharks-puffins-animals-biofluorescence-oceans/
I respectfully disagree :) The way I understand the article and others is that the birds are bioflourescent but they don't yet know why(maybe to attact mates). They don't produce the light, they absord UV light and emit an orange color. They created the glasses to see if the living birds reacted the same as the dead ones under UV light. The article just points out the difference between bioflourescent and bioluminescent. Nat Geo is the only article I've seen that uses bioluminescent in the title, which makes it misleading.
The puffin wearing those sunglasses is adorable lol
I was just going by the article. I would think it probably has to do with attracting fish underwater, rather than a mate, since I'm not sure how effective it would be unless they see UV. Puffins in general are just adorable, and I really like that the scientists are so concerned about their welfare they are postponing research to develop protective eyewear. Definitely an improvement over historical research.
https://news.nationalgeographic.com/2018/04/sharks-puffins-animals-biofluorescence-oceans/
The puffin wearing those sunglasses is adorable lol
I agree though, the safety of the animal should be priority