Talking about turacos
Today I’d like to spend some time talking about the turacos. You may have noticed these personable birds in our aviaries, hopping from branch to branch or making a variety of unique vocalizations. This group of birds belongs to the family Musophagidae. The family name is derived from the words Musa, the genus name for banana plants, and –phagus, a Latin term meaning “to eat.” This explains the common name for some of the birds belonging to this group, the plantain eaters. As the name suggests, these animals are frugivores (fruit-eaters), but will also eat other plant material and occasionally insects and other invertebrates. Zoo Atlanta has two members of the family: the violaceous turaco (Musophaga violacea) and the western plantain eater (Crinifer piscator).
How is the word “turaco” actually pronounced? This is cause for debate even among the bird experts at Zoo Atlanta! One of our birds, a male violaceous turaco, is named Taco in order to create the rhyme “Taco turaco.” However, the word itself comes from the French touraco, which is itself derived from a West African word for these birds, and should properly be pronounced as too-ruh-koh. Sorry about that, Taco.
Today, turacos are almost entirely limited to sub-Saharan Africa. However, the fossil record for these birds also extends into Europe, and a recent study identified the Eocene North American fossil Foro panarium as a member of this group, suggesting that these birds were historically much more broadly distributed than they are today (Field and Hsiang, 2018).
Turacos have some very interesting anatomical adaptations. Birds do not have hands, so instead use their beaks to manipulate food and interact with their environments. Turacos have several oral adaptations , including short and broad bills, fleshy triangular tongues, the ability to move the upper beak relative to the skull (a feature termed “cranial kinesis,” which is seen in some other bird groups – think parrots!), and unique and well-developed uncinate bones of the upper jaw which form an outer brace against the lower jaw and keep the lower jaw from flaring out too much during chewing (Korzun et al., 2003). These are all adaptations for feeding on fruit. Whereas some birds swallow fruit whole, turacos are well-known for chewing and slicing their meals before swallowing.
The feet of these birds are referred to as semi-zygodactylous (zygo – for split and dactyl – for toe). Whereas birds like parrots are completely zygodactylous with digits 1 and 4 facing backwards and digits 2 and 3 facing forwards, the fourth digit of turacos can transition between a forward and backward position. This is probably an adaptation for branch-hopping to obtain fruits. While they are poor flyers, they are excellent runners and very hard to capture!
One of the most striking features of turacos is the wide array of vibrant colors in their plumage. Did you know that turacos as a group are one of the few birds that can produce true green as a pigment? This is due to turacoverdin, a copper-based pigment which is found in the feathers. Combination of this pigment with other pigments such as carotenoids and turacin is responsible for the beautiful colors you see on the birds in our collection. Notice that while plantain eaters have more muted colors, violaceous turacos are an absolute visual treat. Also notice how the feathers on the head lack barbules (sideways projections) and are more hairlike, resulting in the distinct mohawk-like head crest.
Turacos lack a crop (the storage chamber of the esophagus found in some birds), have a large and well-muscled proventriculus (the stomach chamber before the gizzard), have poorly-muscled gizzards, and have poorly-developed to absent ceca (projections off the colon used for fermenting food). Interestingly, other non-related frugivorous birds share these characteristics, including cassowaries. Unfortunately, because fruit-based diets in the wild are very low in iron, birds kept under managed care are especially prone to iron storage disease, in which excessive dietary iron results in iron overload. For this reason, the diets of our turacos are very carefully managed by our nutrition staff and care team.
Next time you’re at the Zoo, come and have a look at our western plantain eaters and violaceous turacos. Come and see if you can spot any of the features that make these birds truly unique. They’re worth taking a couple of minutes (or if you’re like me, hours) of your zoo visit to appreciate and admire.
Keeper I, Birds