Journal #3: Ecological Physiology

From 2:00-3:30 PM on March 9th, I sat on the lawn of the Washington Monument in Washington DC, and observed birds in a grove of cherry trees, and two oak trees. It was 72º and sunny with clear skies and minor amounts of wind. There were people around but the spot I was in was not overrun with tourists. The breeze was coming off the bay that sat a couple hundred meters from where I was. Even though DC is a city, it has many trees so I was able to observe bird species in an environment other than the forests of Vermont. I saw European Starlings, House Sparrows, and Ring-billed Gulls.
The way the different species interact with each other varied. In both the sparrows and starlings, there was definitive flocking behavior, but the starlings appeared to have more of a hierarchy. For starters, only the starlings were making sounds at all. I could hear them all throughout the trees, on the ground, and in the air. And although they were in a group, there was tension. I observed an individual pecking at an apple on the ground, and then another starling came, made calls at the first individual resulting in the first bird's departure. This looked like a show of dominance which makes me believe that the calls from the starlings were a warning of territory control and dominance. I think that even though all these individuals were cohabitating they were not a cohesive unit, and made “threats” at each other to show who was in control. Alternatively, I saw a large group of House Sparrows (around 10 individuals), all in one location under a cherry tree, foraging, and not making a single sound. There was no chirping, no threat calls, no songs. They were all simply eating under a tree, taking dust baths, and sharing the unlimited resources. This looked like more cohesive flocking than the starlings.
The plumage of the Ring-billed Gull and House Sparrow are quite different. The gull is almost completely white while the sparrow is various shades of brown. Although these species can exist in the same or similar habitats, they occupy different niches. Gulls are water birds, so they need much more sleek feathers to cut easier through winds, and their white coloring could help with refracted light off the water and protect them from predators. Sparrows, on the other hand, do not need this advantage. They are living in trees, shrubs and cities and really just need to blend in. Their brown coloration helps them blend into trees and their down feathers help keep them warm. They do not need to fly long distances so it is not as crucial that they be as streamlined as the gull. These two bird species need to adapt to different circumstances because they are not concerned with the same predators or living circumstances.

Publicado el marzo 18, 2020 03:31 TARDE por