When I first received a Foldscope, I planned on exploring the woods near my house in upstate New York with it. However, before I could make it back home, inspiration struck elsewhere in the form of four fluffy individuals found in my friend’s house: budgerigars. Budgerigars – also known as common pet parakeets – are small, long-tailed parrots. Over winter break, I had the opportunity and pleasure to observe these domesticated parrots.

As I observed the birds in their day-to-day activities, I quickly noticed that the yellow one, Sunshine, seemed to constantly peck at himself. Unfamiliar with budgerigars, I asked my friend, who had owned budgerigars for over three years, what Sunshine was doing. He explained to me that the parakeet was preening. For those unfamiliar with bird terminology like I was, preening means that Sunshine was straightening and cleaning his feathers.

Over the next few days, I noticed with alarm that Sunshine was losing a large amount of feathers in a very short period of time. When I expressed concern to my friend, he explained to me that the parrot was just molting. According to him, budgerigars are known for their rapid loss of feathers during their molting period. Put at ease, I was still intrigued by the different types of feathers that the parakeet shed. I had initially assumed that a parakeet’s feathers were all the same, but I saw that I was wrong. They varied by shape, size, and color. Some of the feathers were short and fluffy, some were long and fine, and others looked to be somewhere in between.

I immediately knew that I wanted to observe these different types of feathers with the Foldscope. I hoped that a closer look would help answer the many questions I had about them. Why do budgerigars have different types of feathers? How much do the structures of the feathers differ? What are bird feathers made of? How does this relate to the feathers’ different functions? Or perhaps a closer inspection would reveal something else interesting about the birds and their feathers.

First, I looked at the long, yellow feather. After careful examination of both the feather and the parrot, I determined that it was a tail feather.

Figures 4A-D – Close-up looks at the long, yellow feather.

The feather was fairly structured. As seen in Figures 4A-D, the individual filaments, known as barbs, are very fine. Under the Foldscope, they look like yellow pieces of finely spun thread. The barbs branch together to form barbules, as shown by the upper right photograph. The barbules are distinct from one another, and each one seems to have its own smaller shaft. These barbules are also attached to the rachis, which is the main shaft of the feather. The rachis itself is very interesting. If you expand the upper right photograph, you can see that the main shaft consists of circular structures, which are likely the cells that make up the structure. The upper left photograph suggests that the rachis has two layers: an outer layer and an inner core.

Next, I looked at the medium-sized feather, which was likely a secondary wing feather. Again, I made this prediction by closely examining the bird and the feather.

Figures 5A-D – Close-up looks at the medium-sized feather.

As seen in Figures 5A-D, the medium-sized feather has the same basic structure as the long, yellow feather: barbs branching into barbules that are attached to the rachis. The most obvious difference is in color; this feather is clearly white. A more notable difference though is the difference in the consistency of the barbs. Resembling eyelashes more than thread, these barbs appear to be more fluffy than the barbs of the long, yellow feather. Perhaps this aids the parrot in flying.

Finally, I looked at one of the small fluffy feathers. In better lighting, you can see that it’s not completely white as Figure 3 makes it seem. Rather, it is yellow on top and white on the bottom. I could feel with my hands that the consistency between the yellow parts and the white parts were different. I’m not quite sure where this feather came from on the bird, but I would guess that it came from his chest.

Figures 6A-D – Close-up looks at the smallest feather.

I was particularly interested in the transition from yellow barbules to white barbules, so I focused on that part of the feather. As shown by the lower two photographs, the consistency gradually changed from fine to fluffy as you went from yellow to white. The yellow part resembles the medium-sized feather, whereas the white part is more fluffy and delicate looking than either the medium-sized feather or the long feather. You can see in the upper right photograph of Figures 6A-D that the white barbules resemble a ball of cotton. Due to its location on the feather and its consistency, I would guess that the white part keeps the bird warm by acting as an insulating layer.

With all of these findings in mind, I decided to do some research on budgerigars and their feathers. I confirmed many of my predictions and learned that there two basic types of feathers: vaned feathers and down feathers. Vaned feathers are those with a hard main shaft, and down feathers are those with a soft main shaft. I also discovered that the fluffy white part is called the afterfeather. As I suspected, these downy afterfeathers help to insulate the bird by trapping warm air close to its body. Finally, I also learned that the feathers are made of keratin [1]. This makes sense given the feathers’ fibrous appearance underneath the Foldscope.

Now that I know more about the feathers of budgerigars bred in captivity, I wonder if the feathers of wild budgerigars are any different. Are the feathers of domesticated bird species different from wild bird species? If so, how are they different? Would those differences be the result of the domestication process? Exploring the relationship between domestication and feather development in birds will have to be a project for the future if I can ever get my hands on all of those feathers.

I conducted this project as part of Professor Pringle’s EEB321 class at Princeton University.