Field Observation 6: Reproductive Ecology and Evolution
On Sunday April 21st, I went to Centennial Woods in Burlington, VT at 11:30 a.m. The temperature was quite warm, about 70 degrees C, and the morning was sunny with slight cloud coverage. As our time spent birding progressed, the cloud coverage became thicker but the temperature remained warm. The first bird seen was a Pileated Woodpecker beginning to peck at the trunk of a tree. Since the tree was dead, it is most likely that this Woodpecker was creating a nesting site for offspring. Two Red-winged Blackbirds, a male and a female, were seen rustling in a field of goldenrod plants. These individuals were most likely choosing a spot to nest and begin breeding. This species tends to defend its territory, so it makes sense that they were trying to find a spot with the best location and resources. Slightly later on, a House Sparrow was seen sitting in the top branches of a tree. The bird seemed to be very still, even during the approach of humans, most likely because they are very used to living with humans.
Throughout this time period, three Black-capped Chickadees, an American Robin, and two Canada Geese were heard. The Chickadees seemed to be calling to each other, possibly signaling a food source or a good nesting site. These birds are very social, so it makes sense that they would be communicating to each other for resources verbally. The American Robin displayed its “cheerio” call from what seemed to be high in a tree. Robins usually nest in trees in wooded areas, so this bird could have found a nesting site and was signaling to its mate. Although I didn’t spot a nest, there could have been one already built that I couldn’t see and the individual could have been calling for its mate to find it. Canada Geese were heard in what seemed to be calling out to each other. During the spring, mating pairs break out from flocks and begin to defend territories, which is probably the behavior that was displayed. Males may have been showing defense mechanisms of territory by honking at one another.
Nesting requirements of House Sparrows are very different when compared to other birds. They are typically found nesting in holes of buildings or other urban fixtures, like streetlights and signs. Since nesting requirements are not very strict for this species, this could be the reason the Sparrow seen was calmly sitting in a tree rather than finding a place to nest. There are many houses and buildings the bird could easily make its home. Unlike the Sparrow, the Woodpecker has a unique place of nesting, usually in cavities that they hollow out themselves. Because of this, Woodpeckers may be more territorial because of the work put into building a nest. The Canada Goose also creates nesting sites unlike either of these two species. Geese prefer open sites, usually near water, and lay their eggs in a hole in the ground. Canada Geese are mainly a monogamous species, so males spend less time guarding females and females can put most of their energy into nesting and brooding.
In response to the mini activity, three Black-capped Chickadees were heard in the 10 minutes of sitting in one spot and listening. The individuals seemed to be fairly close to each other, but ranging from about 15 to 20 feet away from me. Three individuals were heard one after another and this was the only species heard during that 10 minutes. Thinking about where these individuals were in respect to my location put into perspective the sociality and movement of this species.
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