FJ 7: Reproductive Ecology and Evolution

For this entry I observed birds in Norwich, Vermont, on April 21st, 2020, from 8:30-9:00am. The weather was sunny and around 40 °F. I was in a grassy area between a main road and the Connecticut River. The area was down a small slope from the road, and had scattered trees, with a few clumps around the edges. There was a steep slope from the grass to the river which was covered in small brush/bushes. One side faced a wide area of stiller water where a stream meets the river, and there was a marsh-like habitat there. The bank across the river was forested.
I saw and heard a lot of Red-winged Blackbirds, which I expected since they like marshy areas. I saw seven males, but no females. I am guessing that there were females around, but they were probably in the vegetation around the marshy area, since they tend to stay lower and don’t try to attract attention like the males. I saw three geese on the water and four flying above the river. A juvenile Bald Eagle circled above the river for a minute, and then kept flying along the river and out of sight. I saw four blue jays total, two of which were together.
I think the Red-winged Blackbird songs were territorial behaviors in preparation for mating. The males perched in trees and on the grass and sang loudly and often. They were probably defending their territories where their mates were nesting. They usually nest in marshy areas or low vegetation, so it is likely there were some nests and females nearby. If the females were in the lower vegetation or shrubs collecting materials for nests, they would probably use grasses, stems, sticks, and other plants. Red-winged Blackbirds also use wet leaves, decayed wood, and mud to stick the nest together and shape it. They could find all of those in the marsh habitat, so if they were nesting there they wouldn’t have to go far.
Blue Jays, which I also heard singing, use different nest materials- mainly roots and twigs from trees. If the Blue Jays I saw were nesting in the nearby small trees, they probably wouldn’t have the prime habitat. This probably means that they have relatively low fitness compared to others of their species, since they are not able to claim and defend prime habitat. Nesting would be better near the marsh or across the river, where the trees were denser and larger, so they would have thicker and taller branches to build a nest on.

Link to sound map:
https://docs.google.com/document/d/1AQCPVhh6MWnP2_6RvPCPPHgdRAcRSdmCMiI0ulT0xwU/edit?usp=sharing

Publicado el 23 de abril de 2020 a las 03:46 AM por juliecal