Color: Perception of and by Caiques
There are two sides to bird perception, there is how we perceive our parrots and then there is how our parrots perceive us. When we look at parrots, we see color, and some are more pleasing to us than others. The coloration of caiques (Pionites sp.) is especially pleasingly. However, their color varies from bird to bird even within each species. We can alter their color by modifying diet and possibly by a method called tapiragem, but these can be deleterious for the bird. There are also color-mutations of parrots, but there are few if any of these for caiques.
How parrots see the world is another matter. While we have two types of light detection cells in our retinas, and three types of opsins within those cells, parrots have three types of light detection cells and four types of opsins. Because of this, scientists believe that many birds have an enhanced visual prowess particularly in the near ultraviolet range. This led me to explore how a caique’s plumage appears in the ultraviolet and with Prof. Davidhazy; I discovered that the apricot colored feathers on their nape fluoresce a bright yellow when illuminated with near ultraviolet light. On the other hand, we saw no real differences between the sexes by either fluorescence or UV reflectance.
Perceptions can be deceiving. People have always appreciated the bright colors of birds and especially parrots. Only recently have we begun to appreciate how birds see each other and us. In this presentation, I discuss the variability in color of parrots of the same species, particularly caiques. Generally, we find their coloration very pleasant, but we still keep looking for ways to alter their coloration. Modern aviculturalists are especially fascinated with color mutations; however, aboriginal peoples were more interested in manipulating a parrot’s plumage to produce aberrantly colored feathers. We are also learning that our bird companions perceive the world differently than we do, and our colors may not be their colors. They may see more colors. The goal of this talk to stimulate an appreciation of color perception and its complexities.
How we see caiques and other parrots.
The colors of species and subspecies.
Most taxonomists divide the caiques into two species: Pionites melanocephalus and Pionites leucogaster. They further divide P. melanocephalus into two subspecies or races: P. melanocephalus melanocephalus and P. melanocephalus pallidus. They also further divide P. leucogaster into three subspecies or races: P. leucogaster leucogaster, P. leucogaster xanthurus and P. leucogaster xanthomerius. All of these separations are based on their plumage color patterns. Not everyone agrees with this. The late Dr. George Smith believed that caiques belonged to one species or super-species, and that P. leucogaster is really a subspecies of P. melanocephalus and proposed the scientific name P. melanocephalus leucogaster for it. There is even a recent taxonomic work that suggests that the Pionites genus should include the Pionopsitta parrots as separate species within it (9). These separations and affinities are largely based on the birds’ colors and shapes.
There is a problem with this, at least for caiques. There are no clear lines separating the different color forms. Yes, we have clear descriptions that define of the different subspecies, but a closer look gives us doubts. The reason is that when you look at the zoogeography of caiques you find that it is very difficult to draw a line separating the subspecies. While there is a clear difference in the appearance of the black-headed whose range is largely north of the main trunk of the Amazon River from that of the apricot-headed white-bellied whose range is south of the river, within the ranges of the two species there is wide variability in phenotype. The evolution of the two species seems to be following a clear pattern. In the past, there was what evolution biologists call a “vicariant event,” i.e. a physical bifurcation in range of the protospecies. In the case of caiques, it clearly seems to have been the rise of the Andes Mountains, which forced the Amazon River to flow east. This split the proto-caique’s range. The explanation of the evolution of the caique subspecies afterwards, however, is more controversial. There are two main views. The first was set forth by Haffer (4). In his theory, there were a series of vicariant events in which “islands of life” called “refugias” formed when there was an expansion of arid areas into Amazonia. In the other, the evolution of subspecies was due to the large ranges of the two species resulting in the birds at distant parts within the original range diverging to generate new phenotypes. Evolutionary scientists call this a parapatric mechanism. Whatever the mechanism, currently there are zones between the ranges of the different subspecies where wild caiques do not conform to what people define as one form or the other.
The point of this is that caiques, even in the wild, exist in a variety of phenotypes that do not conform to the criteria that define the species and especially the several subspecies. Both Fry (3) and Novaes (8) made particular mention of intermediate forms of caique in the zone separating the ranges of P. l. xanthurus and P. l. leucogaster. Similarly, Low (5) and others have noted a gradation in thigh color in the large expanse separating the well defined forms of P. m. melanocephalus in the east and P. m. pallidus in the west. Thus, we need to be careful of how we think about species and subspecies.
The color of individuals in the wild.
Added to this is the appearance of what may be atypical color morphs of caiques within the accepted ranges of the different subspecies. In the Carnegie Museum collection, there is a black-headed caique with green tinged thighs from the Mara River in French Guiana, in the heart of the range of the nominate P. m. melanocephalus. One would expect the thighs on this bird to be completely orange. You can also find a picture of a P. l. xanthurus with green thighs on the internet. Thus, you cannot state precisely what the characteristics that any of the subspecies should have.
Color modification by interbreeding of species and subspecies.
Next, there is the interbreeding of the species and subspecies. I am sorry to say we know very little about what happens when you breed a P. melanocephalus with a P. leucogaster. Surprisingly, one of the few reports on this is from one of the earliest breedings of caiques by Lady Poltimore. Her pairing of a P. m. pallidus with a P. l. leucogaster produced four chicks but only one survived. She noted that it was most similar to the P. m. pallidus, except it had green thighs. I suspect that there has been far more cross-breeding than we aware of. We know that some of the early breeding successes at Busch Gardens in Tampa were crosses between P. l. xanthomerius and P. l. leucogaster. It that era, when there were few caiques in captivity and there was no good way to sex birds, they had do the best they could. Some of the Busch Gardens birds have entered the gene pool in the United States, and occasionally one hears of a P. l. xanthomerius chick developing green-thighs. However, we cannot know if this is a result of hybridization in the past or just a normal variant. I received a very interesting picture of what may be a hybrid that I find it particularly charming. It is of a caique with a chevron of black feathers set into the typical apricot colored feathers that would be on the crown of a P. leucogaster. This bird was 13 years of age, and thus this coloration was unlikely due to it being a juvenile. Sad to say, we remain very naïve about color inheritance in caiques because of our castigation of breeders that happen to interbreed them.
Cosmetic or adventitious color alteration.
Cosmetic or adventitious colors are not intrinsic to the plumage, instead the bird acquires the color from its environment. Perhaps the most noted bird for doing this is the Bearded Vulture (Gypaetus barbatus) (7). The neck, head and under parts of this vulture are often a “rich rusty-orange color.” They acquire this coloration from soils and muds rich in iron oxide. Caiques in the wild also seem to color themselves cosmetically, and I know of no other parrot that does this. In early French references, the breast of caique specimens collected from the wild are often said to have an “Isobel” color. Isobel, is a shade of chestnut. If you ever examine the caique specimens in the collections of natural history museums, you can always pick out those collected from the wild from those that had been kept in captivity because of this. I speculate that caiques acquire their Isobel color from their habit of rubbing their breast across twigs, limbs and leaves rich in tannins. When I pointed this out to one of the curators at one museum, she tried to wash one of the breast feathers with soap and water, but she could not remove the color since is was permanently set. We know that tame caiques like to rub their bodies against wet surfaces. Pet owners call this “surfing,” and ornithologists call this “leaf-bathing.” Maybe we should not call this “bathing,” but a “breast-staining” process.
Color feeding of parrots.
We are all aware of the color feeding of canaries and flamingos, but we do not usually color feed parrots. In Amazonia they do. The indigenous peoples often practice color feeding parrots to give them what they feel is a more pleasing appearance. The science behind this color feeding, however, is very different from that of canaries. In canaries and other birds, color feeding consists of supplementing their diet with foods rich in carotene. The gut absorbs this pigment and the blood transports it to the feather follicle where it is incorporated into the developing feather. This mechanism does not apply to parrots because the color of their feathers is due to a different set of pigments not found in their diet but we think are synthesized in the feather follicle. These are the psittacofulvins. Further, the color feeding of parrots is unrelated to the deposition of the yellow to red psittacofulvin pigments but rather the failure to deposit the dark melanin pigments is the bird's feathers. In caiques, and in some other Neotropical parrots, you can achieve this by feeding a fat rich diet. When I first started to breed caiques I purchased a hen that was a phenotypic pied, i.e. she had a scattering of yellow feathers among the feathers on her back that are normally green. When I purchased her, she was on a diet rich in sunflower seed. After I switched her to a diet without sunflower seed, she eventually molted to a normal coloration. In South America, the indigenous people achieve the same result by feeding birds a diet rich in a number of fats including dendé oil (red palm oil) or, alternatively, the fat of several fish species. I highly recommend that you do not do adapt this practice because one report notes that is causes severe liver damage (11).
Tapiragem is another practice by which the indigenous peoples of South America alter the color of the feathers on a parrot. In contrast to color feeding, which causes a systemic alteration in feather color, in this case, the practitioner alters the color of individual feathers. In tapiragem, the native pulls the feathers and applies an ointment to the skin and into the follicle. The feathers, which are normally green, then grow in a clear yellow often with a tinge of red. The Indians place high value on these feathers and use them to make various ceremonial adornments that are strikingly beautiful. Most modern reports suggest that the mechanism behind tapiragem is the repeated trauma of pulling the feathers and not any specific ointment, but a good proof of this is lacking. I have not heard of this practice for caiques, but there are many reports of this for macaws and Amazon parrots.
For modern aviculturalists, however, the favorite way of altering parrot color is the selective propagation of chance mutations. There are many of these for other parrots, and people have written books on the genetics of the color mutants of budgerigars and cockatiels. A general literature is also developing for parrots (6). As of this time, there are no well-documented color mutations of caiques. There are some interesting phenotypes, but no one has confirmed them as mutations in breeding experiments. There is one possible example of a true pied. The only reason to believe it might be is that pied trait present only in the male member of a breeding pair and we know that this is usually a recessive sex-linked trait. A year or two ago I received a picture of what appeared to be an olive mutation, unfortunately its owner reported it had died shortly after fledging from unknown reasons. More recently, I received a picture of a bird that looks like a lutino, but I suspect it is more likely a “dilute” since the lutino trait is usually sex-linked and there are two chicks of the same phenotype from the same pair—one male and the other female. My reason for skepticism about declaring a color variant to be a color mutation comes from what I have learned about thing such as color feeding and tapiragem. Thus, there probably already exist color mutants of caiques, but we need to pay scrupulous attention to their diet when a mutation involves melanin deposition. Still, it is very likely only a matter of time before we have a whole set of caique color mutants.
How Parrots see the World
On Bird and Parrot vision.
Our birds see thing differently than we do (2). Their eyes are flatter than ours are. While our lens and fluids in the eye have a yellow cast, theirs are clear. More importantly, while we have two types of light detection cells that possess three kinds of molecules called opsins for detecting light; birds have three and possibly more kinds of detecting cells and they possess four kinds of opsins. Further, they often have tinted droplets that may serve as optical filters associated with some of their light detection cells. In particular, scientists believe they are able to see further into the ultraviolet light range than we do. However, we really have no idea what their color palate is like. It seems likely though that parrots have a greater richness in visual perception than people do. As a way of understanding this, consider people with the dichromatic form of human color-blindness. People with this form of color-blindness lack one of the cone cell opsins, and do not have the range of color perception of people without this malady.
To get an idea of just what my caiques are seeing, I enlisted the help of Prof. Davidhazy at the Rochester Institute of Technology. At the time, I was looking for features that might allow me to distinguish the sex of my caiques. He took pictures of my white-bellied pair in white light, their fluorescence when exposed to short wave UV, and finally the light reflected when illuminated with short wave UV. I had already examined my birds for fluorescence using a black light and knew other parrots possessed fluorescent feathers (1), but the pictures Prof. took of the fluorescence were stunning. The apricot feathers on their head and nape fluoresced a bright yellow. Unfortunately, we were unable to discern any difference between the sexes by fluorescence or UV reflectance. Recently, Santos (10) reported that she was able to determine the sex of blue-fronted Amazons (Amazona aestiva) which to us appears monomorphic. Her group did this using a method called multiple-angle spectrometry. This method tries to mimic the tetrachromic vision of birds. If correct, this work will go a long way to understanding just how parrots see.
Finally, a number of years ago one of the participants on a computer chat group I was a member of made an unusual observation. Her son had dyed his hair with a fluorescent orange dye. He was after the punk look. What he did not expect was that their pet caique took an instant interest in him. Before he dyed his hair the bird usually ignored him, but afterward the caique wanted to be with him all the time much to the chagrin of the young boy. This would seem to suggest that color is an important signal to caiques, and we are very naïve as to how they see and respond to it.
1. Boles, W. E. 1990. Glowing parrots--need for a study of hidden colours. Birds International 3:76-79.
2. Cuthill, I. C. 2006. Color perception, p. 3-40. In G. E. Hill and K. A. McGovern (ed.), Bird Coloration., vol. 1. Harvard University Press, Cambridge, MA.
3. Fry, C. H. 1970. Ecological distribution of birds in north-eastern Mato Grosso State, Brazil. Anais da Academia Brazileira de Ciências 42:275-318.
4. Haffer, J. 1977. Verbreitung und Hybridisation der Pionites papageien amazoniens. Bonner Zoologische Beiträge 28:269-278.
5. Low, R. 2003. Caiques. DONA Publishing, Czech Republic.
6. Martin, T. 2002. A Guide to Colour Mutations & Genetics in Parrots. ABK Publications, South Tweeds Head, Australia.
7. Montgomerie, R. 2006. Cosmetic and adventitious colors, p. 399-427. In G. E. Hill and K. J. McGraw (ed.), Bird Coloration, vol. 1. Harvard University Press.
8. Novaes, F. C. 1981. A estrutura da especie nos periquitos do genero Pionites Heine. (The species structure of the parrot genus Pionites psittacidae aves). Boletim do Museu Paraense Emilio Goeldi (Zool.):1-21.
9. Rodner, C., M. Lentino, and R. Restall. 2000. Checklist of the Birds of Northern South America. Pica Press, Sussex.
10. Santos, S. I. C. O., B. Elward, and J. T. Lumeij. 2006. Sexual dichromatism in the blue-fronted Amazon parrot (Amazona aestiva) revealed by multiple-angle spectrometry. Journal of Avian Medicine and Surgery 20:8-14.
11. Sick, H. 1993. Birds in Brazil. A Natural History. Princeton University Press, Princeton.