Traits Associated with Range Sizes and Driver of Individual Species Diversity of American Birds

Morgan Novello, Verrazzano Class of 2025, completed major in Biology, and minor in Italian

I did not know where to begin when it came to my capstone research. Luckily, I had just taken Professor Manne's biology statistics class and she was looking for students for an independent study. I responded right away to see what it was about. During out first meeting she mentioned that we would be studying birds and their traits, and I knew that this would be right for me. My grandad and I used to watch birds in the park when I was younger. He passed a little before the meeting and it gave me another chance to connect with him.

Research with Dr. Manne began by using the most significant traits of birds to see how they related to range size. When you think of birds you may assume that small birds move further because they have less weight to fly around. For instance, a larger body size may directly expand their range due to interactions with resources and environment, but having a larger body species leads to having lower reproductive rates.

So many different traits could mean so many things and we wanted to look into it further. There are many more traits that go into it such as habitat, diet, clutch size, dispersal ability, and fecundity. We took data from three parts of the US: Eastern, Western, and Spanning (meaning the area from east to west). Determining the importance of these traits would allow us to analyze multiple factors.

For the results, the direct relationship between range size and migratory behavior was positive and only significant in the western and eastern areas. Body size was positive everywhere but the east. This meant that in the east smaller body size meant bigger range size.

The next part we wanted to understand was the relationship between the number of individuals and the number of species in an area. In this study, we wanted to see which bird species drive changes in this relationship over time. We used long term (30 years) of bird abundance data. We also used the jackknife regression technique, which was so cool to me. We took one bird to see how the slope changed. By using this, we saw which species whose removal caused bigger changes in this relationship. It showed us patterns of biodiversity. The number of years that a species caused this change varied a lot and this suggested that not all species contributed equally to community structure. Range size was very significant in both the first and second parts of our research.

I expected this capstone to be challenging and it sure was. Writing this paper and reflecting on these past two years took a lot of effort and time. There was so much that went into it. It was not just about writing a paper. I had to research each of these birds and also use a coding platform (R studio). It took a lot of time but I feel very accomplished. What I am taking away from this research experience is my love for birds is renewed. It was so interesting learning all these things about them and doing all this research, and the statistical side of it and learning and using what I learned in class was a great application.