A lot of first-time Gouldian parents are disconcerted when they see the mouth markings, or nodules besides their babies’ mouths. “should I scrape them off?” “What are they??” “Do they hurt?”

Mouth markings are simply nature’s way of taking care of the flock. If you look at other Estrildids’ mouth markings, theirs look weird too, although each one of these grassfinches has a different sort of mark.

Mouth Markings May Help the Parents See

One theory I’ve always heard is that Gouldian finches nest in the back of dark cavities, so they need the mouth markings to see how to feed the babies. Makes sense, right? These markings, properly called papillae, luminesce — so a parent would be able to see them if there’s the tiniest bit of light available. Note that they aren’t phosphorescent, as many believe. They simply reflect light.

Mouth Markings May Help the Parents Discern

Another theory about the mouth markings on finches is based on the fact that every species of finch has different markings. So someone theorized that, if the nest is invaded by a parasitic species (a bird that lays their eggs in another bird’s nest, so the babies are raised by them) the parent birds will notice the different marks and know those are not their babies. One scientist tested this out by painting over the markings. He noticed that the babies without markings weren’t tossed from the nest, as we might suspect, but the parents fed them less than the others.

More Ideas About Mouth Markings

Some people believe that unhealthy chicks have duller markings, so the parents can distinguish healthy and unhealthy babies. Still others think that it helps them notice which chicks are older, since the markings are spaced further apart as the chick grows, and they eventually disappear altogether.

Conclusion

Whichever theory you ascribe to, one thing is for sure: the mouth markings are just a little weird, and they freak people out. That’s just one more thing that makes Gouldian finches so fun.

References

Reduced growth but not survival of chicks with altered gape patterns: implications for the evolution of nestling similarity in a parasitic finch, Justin D. Schuetz https://www.sciencedirect.com/science/article/pii/S0003347205001995 accessed 11/18/2019.

What’s Up With the Weird Mouths of These Finch Chicks? Schweta Karikehalli, https://www.audubon.org/news/whats-weird-mouths-these-finch-chicks# accessed 11/18/2019.

Why are there spots in these birds’ mouths? Rickey Kinley, http://blog.cincinnatizoo.org/2014/01/28/why-are-there-spots-in-these-birds-mouths/ , accessed 11/.18/2019.