Arquivos de periódicos de abril 2019

08 de abril de 2019

Field Observation 3: Migration

On April 7th from 1:00 p.m. to 3:30 p.m., me and two other classmates went to the Urban Reserve by the waterfront of Lake Champlain. The temperature was about 50°F, but the sky was overcast and slightly windy. The Reserve is near the lake, in a slightly wooded area, which might have influenced more birds to be present during our walk. During this time, we saw a flock of American Crows, 3 Herring Gulls, 2 American Robins, a flock of Cedar Waxwings, and 3 Black-capped Chickadees. As the weather gets warmer, we are starting to see more bird species present, along with more species that migrate North in the spring and summer.
Throughout our walk, we saw 3 Black-capped Chickadees separately. The birds were most likely alone because they are a resident species that do not migrate, so it’s not necessary for them to travel in flocks. This species is able to withstand the cold temperatures of Vermont because of their ability to undergo facultative hypothermia and to change their diet based on available resources. The next species seen was the American Crow, where a flock of about 10 birds was seen circling overhead, all of them exhibiting loud “cawing” calls. They were most likely traveling in a flock because they were migrating from a warmer climate. These species are year-round residents of Vermont but may travel short distances South. This could be the reason that many more flocks have been seen recently compared to the winter time. As with the American Crow, the Herring Gull is also a year-round resident of Vermont, but some flocks may travel South for the winter. Three Herring Gulls were seen, with the first flying overhead and the next two following along a few minutes later. Both Gulls and Crows are facultative migrants, so it is likely that these individuals were in Vermont year-round, but the increased prevalence of these birds could be due to the introduction of spring.
The next two species seen are both obligate migrants, that travel to South of the United States in the winter and travel back up in the spring and summer. Two American Robins were seen in what seemed to be a display of aggression. Robins are less social during the day because they are defending their breeding territory, so this could have been an altercation over territory. The advantages of an early migration North could be that there’s more available habitat, which will lead to less altercations, but a disadvantage could be limited food sources. Unlike the Robins, Cedar Waxwings are sociable and non-territorial. A flock of about 8 Cedar Waxwings was seen flying near the tops of trees and had probably recently arrived in Vermont. Because this species is social with members of their flock, these birds probably have advantages when foraging, which is why they have migrated early. The disadvantages could be that there is not much fruit available for feeding, but this is counteracted by the increased foraging efficiency of group living.

Mini Activity: Each obligate migratory bird probably travels roughly 1,000 miles. The obligate migrants (2 American Robins and 8 Cedar Waxwings) probably travelled about 10,000 miles combined. The facultative migrants (10 American Crows and 3 Herring Gulls) probably travelled much less based on their range. I estimated these individuals will travel about 300 miles, for a total of 9,000 miles. The total range traveled for all migrant species seen would be around 19,000 miles total.

Posted on 08 de abril de 2019, 10:19 PM by mkerner mkerner | 5 observações | 0 comentários | Deixar um comentário

15 de abril de 2019

Field Observation 5

Posted on 15 de abril de 2019, 06:20 PM by mkerner mkerner | 6 observações | 0 comentários | Deixar um comentário

23 de abril de 2019

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.

Posted on 23 de abril de 2019, 02:01 AM by mkerner mkerner | 6 observações | 0 comentários | Deixar um comentário

30 de abril de 2019

Field Observation 7

Posted on 30 de abril de 2019, 01:17 PM by mkerner mkerner | 6 observações | 0 comentários | Deixar um comentário

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