maliabertelsen's Journal

I started birding at 8:00am, it was sunny but a little windy with a temperature of 39F. I walked down the street to Pomeroy Park and stayed there sitting still in various parts of the park, so the habitat was urban/urban green space with some trees a clearing and some bushes. I think this habitat is why it was more difficult for me to take pictures of the birds, they mostly stayed in the trees or bushes or were flying, and if they were on the ground it was not for very long. This could be because early April is before breeding season so each of these birds is considering their energy costs and which will be the most profitable for them to invest in.

The year round residents that I observed were the House Sparrow, Ring-billed Gull, Tufted Titmouse, Blue Jay, Northern Cardinal, and European Starling. I think they forgo migration because their diets are not solely reliant on insects, instead they are able to forage and eat various berries and other plants that are available year round. The physiological and behavioral adaptations that allow them to survive year round in Vermont include being able to poof themselves so there is an increased amount of feathers around them to trap body heat. Furthermore by being cavity nesters such as Tufted Titmice, they are able to access the best nesting sights which increases their reproductive success. Ring-billed gulls are also able to conserve body heat through the winter by covering apteria parts of their body this includes sitting on their legs or standing on one leg and tucking the other. Furthermore following Burgmann's rule that body size increases with latitude these birds bodies may be more suited for the thermoregulation necessary for the winter opposed to smaller migratory birds such as hummingbirds. The cardinals, house sparrows, and blue jays especially appeared to be interacting with one another perhaps to have an advantageous edge on other species for nesting availability and resources.

The facultative resident I observed was the American Robin. They are likely coming from a place that is southern but still relatively close to Vermont, such as North Carolina. Although in milder winters it is possible that robins will stay year round. The American Robin is making its way back to Vermont for breeding because as the weather is warming up more food is available and the habitat is becoming ideal for nesting. This includes new vegetation which better conceals nests and there being more available nesting material. The robins I saw were all on the ground looking for food which could indicate fueling up after migration and before breeding.

The obligate migrant I saw was a Turkey Vulture. It could be advantageous to arrive in Burlington in early April in order to secure optimal territory for feeding then breeding. Since migration is one of the highest energy cost events that a bird will experience it will want to space it out from breeding which is the next high energy cost event. By arriving early, the obligate migrants allow themselves time to feed and establish territory from other birds which gives it a greater advantage during breeding. Since Turkey Vultures can winter as far south as Central America, their timing of migrating to Vermont is reactive to the amount of daylight they are experiencing, as such they can have a disadvantage of not knowing the climate of where they are migrating to. This could mean unexpected spring snow storms (like what we had last week), this could harm their ability to forage for food or have adequate shelter and overall ends up being more energy costly after migration.

Mini activity: The House Sparrow, Ring-billed Gull, Tufted Titmouse, Blue Jay, Northern Cardinal, and European Starling would have a wintering rage that stays within the area that I observed them. A robin traveling from Durham, NC to Burlington, VT would cover a total distance flying of 1,057.79 km. A Turkey Vulture Traveling from Miami, FL to Burlington VT would cover a total flying distance of 2,168.34 km.

On April 18, 2021 I went to the Richmond park in Richmond, VT and sat by the Winooski River starting at 4:00pm and walked along the banks until 5:30. It was clear and sunny and was about 50 F. This was mostly a riparian area because it was all along a river bank.

Sunday April 25th I started birding at 6:53pm it was partly cloudy, had rained earlier in the day and was about 45 F. I was at Ethan Allen Homestead so the habitat was a mixture of denser vegetation, riparian areas, and open fields.

At the beginning of birding there were lots of audio displays from the birds that seemed to correlate more with an establishment of territory because of the added winged and head displays that looked more dominant to me. However, there were also some calls and responses which I think indicate more of a mate selection.

When I first started birding I was standing on the edge of a field of cattails with a few trees and bushes that were dispersed inside the patch of cattails. I saw 6 male Red-winged Blackbirds that were distributed uniformly throughout the patch, usually in a tree or bush. In particular, there was one male who stayed the longest in this patch, starting in a tall bush and after about 10 minutes moving to a different tree in the patch while other males were less persistent. I think that this male was potentially more fit than others because of its persistence and it having the most dominating call compared to the others, also because it didn't look like any other male was challenging it directly. This male would also extend its wings and tilt it's head up when it was calling. After observing this I believe this was an audio and visual display related to territory/nest selection, also because there appeared to be females in the cattails gathering nesting materials. I believe that this section of dense vegetation is where the red-winged blackbirds are nesting because they build nests lower among shrubs.

I saw some other nests in older trees that were higher up and looked like robins nests because of how dense the materials were woven together. Therefore, I think the robins are more likely to be nesting in the forested areas of the property while the red-winged blackbirds are more likely to nest in dense sections of cattails. These habitat requirements are different because one bird nests lower down while the other nests higher up, furthermore, it seems that the American Robin relies on physical distance from potential predators while the red-winged blackbird relies on coverage and being camouflaged. I also saw two a very small nests that were in lower bushes among small dense branches located near the river. I don't know what kind of bird made this nest, but it would seem that its habitat requirements maybe also rely more on being covered and blending in, especially if they nest when leaves and flowers have bloomed.

It looked like the robins were gathering more of straw-like almost stringy material while the red-winged blackbirds looked like they were gathering more fibrous materials. In order to find the straw/stringy material I think that the robins would have to go places were there have been ruminants of tall grass and other plants that have been buried under the snow all winter. Thus closer to fields and forested areas would be ideal.