Nestling coloration is adjusted to parent visual performance in altrical birds

The purpose of this study was to determine if there was a relationship between the coloration of nestlings and the visual capacity of the parent in altrical birds. The researchers wanted to see if coloration varied during begging displays, such as when a baby bird begs for food, based on the parent bird’s capacity to see certain types of light. The researchers studied 22 species of birds, some of whose eyes were UV-tuned (UVS), and others whose eyes were violet-tuned (VS). The researchers collected their data in several steps. First, they assessed the different types of eyes of each species of bird, including the UV and violet capabilities. There was not prior research on this for each species, but they were able to make inferences based on related species. Next, using Ocean Optics spectrophotometers, they measured the various color components of the nestlings and the nest, for characteristics such as UV intensity, UV chroma, yellow intensity, yellow chroma, and brightness. They separated the nests into hole-nests and open-nests to standardize the data. They hypothesized that the nest and the nestlings would show contrast in some areas to make the nestlings visible to the parents. They also hypothesized that there would be a correlation between the way the parent’s eye worked and the type of light that the nestlings gave off, such that they used the same type of light. This would make it easier for the parents to see the nestlings. They found that, in hole-nesters, UVS eyes perceived the coloration of the nestlings better than VS eyes. Furthermore, once nest site was controlled for, it was found that coloration was associated with type of eye. Nestlings of UVS parents displayed more ultraviolet and yellow characteristics than those with VS parents. In conclusion, this study successfully showed a correlation between the parent’s visual system and the nestling coloration involved in begging behavior.

This article is very relevant to our discussion of visual systems. It not only discusses how a specific visual system receives certain types of light, but it discusses light production. This article supports the topics related to visual systems discussed in class and provides a reasonable example to which concepts discussed in class can be applied. For example, in class we discussed the light spectrum and how light is produced. Most animals are able to see the visual spectrum as well as other types of light, such as UV. This article provided a great application of this concept as various species of birds were able to detect UV light whereas others could only detect violet light, which is just below UV light on the spectrum. Furthermore, this article used several other characteristics of light, such as chroma and brightness in data analysis. Because it was taught in class, I was able to develop a better understanding of how the study was done. Brightness is based on the reflectance of a surface and chroma is the saturation of color; knowing this allowed me to understand the data collection and actually relate it to the appearance of nestlings. Furthermore, we discussed how light is perceived by the eye of an animal. We were given various examples of types of eyes and how they function, but this article provided a great example of a bird’s eye. This study was effective in relating the type of light transmitted to the receptive capabilities of the recipient. Overall, this article provided a great example of visual systems and light production and reception which could be used to extend upon material learned in class.