What are Mouth Markings?

There are different theories concerning the importance of mouth markings in nestling estrildid finches. Each species has unique patterns that can be easily seen on the palate of a gaping chick. One function of the mouth markings might be to act as 'guides' for the parent bird to find the mouth of the young chick in a dark nest cavity. The high contrast marks are easily seen and are sometimes helped even further with light-colored fleshy flanges or with light reflecting nodules like those found on the Gouldian finch and parrot finch family. These high contrast markings combined with head movements and begging cries may also act as a trigger response to stimulate the parents to feed the chicks. Another function for the mouth markings and the reason why each species has its own pattern might be to identify the chicks in the nest from another (parasitic) species. Some birds are able to distinguish and reject intruders to their nest. I have had zebra finches who selectively rejected owl finch chicks that hatched with their own chicks. As aviculturists, being able to identify a chick by its mouth markings can be an asset. I often use the mouth markings to identify chicks in mixed clutches that have been fostered. They can also be used to identify tossed chicks in mixed aviaries, or to identify a nest of surprise chicks that you're unsure of their parentage. Another thing to be aware of is the effect of mutations on the mouth markings and the attention the parents may or may not give that chick. Often, the dilution seen in the plumage is also seen in the mouth color and the markings. White or albino birds often lack any color at all in their mouth markings and this can sometimes lead to chicks that lag behind or are not fed at all if mixed with chicks with normal mouth markings.