FJ5

Date: 4/3/21
Start time: 3:15

End time: 4:45
Location: Shelburne Bay Park
Weather: Clear and sunny sky, temperature around 42 degrees, 5 mph winds from the north
Habitat(s): mix of coniferous and deciduous forest, shoreline of Shelburne Bay, open field on the edge of the park

I saw and heard many Black-capped Chickadees throughout this trip. Black-capped Chickadees are year-round residents of Vermont. Staying up north all year means physiological and behavioral adaptations are required to survive winter months. Chickadees have a lot of insulating feathers (down) that help keep them warm. They can also puff up these feathers for added insulation. Chickadees are also able to lower their body temperature at night, torpor, to decrease their metabolism and conserve energy. Another key to chickadee survival is their impressive memory. According to a Bird Note podcast, Black-capped Chickadees have a larger section of their brain responsible for spatial memory than other birds. This is important because it allows them to store food all over their territory to have available throughout winter. Also, Black-capped Chickadees are cavity nesters which provide warmth and shelter from harsh winter conditions. Additional behavioral adaptations to staying warm include shivering and finding a sunny spot to sit. Another year-round resident I saw, if I identified it correctly, was the Golden-crowned Kinglet. These tiny birds also foregoes migration out of Vermont and are well suited for the cold. According to their All About Birds page, Golden-crowned Kinglets winter in places where the temperature can reach 40 below at night. Both these species have found the costs of migrating to outweigh the benefits.

I also saw a few species that migrate depending on the conditions, known as facultative migrants. The first of these birds I encountered was the American Robin. Robins are year-round residents in most of the US, however they do have wintering grounds in areas of southern California, northern Mexico, and Florida. I also saw a good amount of Canada Geese in the bay. Although Canada Geese can be year-round residents in parts of Vermont, they also winter in some southern states including North Carolina. I also saw a pair of Common Mergansers who also seem to be year-round residents, but also can migrate short distances in the non-breeding season. I also saw two Turkey Vultures circling over the open field. Turkey Vultures breed in Vermont but migrate short distances to southern states. With the warmer weather we’ve had here these facultative migrants are returning. With the Common Merganser and Canada Goose, the lake is no longer icy, and they can more easily be in the water closer to shore. This also means more aquatic food is available to them. For the Turkey Vulture, the melted snow and warmer temperatures mean more creatures and venturing out and more at risk for ending up as roadkill. Therefore, being up here in Vermont now offers the scavenging Turkey Vultures an increased food supply. Temperature and food also would facultative the arrival of American Robins if they migrated south. The warm temperatures and exposed ground mean more food for the robins.

I did see one species that may be an obligate migrant. As I was heading to my car to leave, I saw a large dark bird with a white belly heading towards the water. At first, I thought maybe it was a Bald Eagle because of the white I saw, however I soon found out it was an Osprey. I was at the parking lot exit and all of a sudden it was flying right towards my car with a nice sized fish in it’s talons! Looking on All About Birds, I discovered that Osprey breed up here while wintering in southern Texas, the coasts of Mexico and Central America, and the Dominican Republic. Since Osprey migrate quite far distances to the south, they seem to be more obligate migrants. An advantage of an obligate migrant arriving up north in early April would be the early establishment of a territory. Arriving early means less competition for a good territory. A disadvantage for arriving now is that the conditions are still unpredictable. However, the Osprey mostly rely on the lake for food and since the lake is no longer icy this is not too much of an issue.
(Bird Note podcast: https://www.birdnote.org/listen/shows/chickadees-winter)

Mini Activity
Osprey from Yucatan, MX– 1,874 mi
Canada Goose from NC – 751 mi
Robin from FL – 1,139 mi
Turkey Vulture from NC – 675 mi
Common Merganser from MA – 122 mi

Total: 4,561 mi

Posted on April 5, 2021 01:40 PM by cjclark6