Journal 5

March 29, 2023
Start time: 10:50 AM
End time: 12:05 PM
Location: Centennial Woods, Burlington, VT
Weather: sunny, few clouds, low 40s, light breeze
Habitats: suburban edge, deciduous woods, creek area, some open patches/edges

In Centennial Woods today, many year-round species were seen, and one migratory species: Ring-billed Gull. On the forest edge, walking in, I saw American Robins, a very vocal Tufted Titmouse, and some Black-capped Chickadee. American Robins can survive Vermont winters because of their adaptations, though most migrate for the winter. They fluff up their feathers to create space and insulation under their down feathers that keeps their core temperature at 104° F. This is really only effective as long as they stay sheltered and dry. Their feet do not get cold because of countercurrent exchange: blood flowing to the feet warms blood flowing from the feet. In the warmer months, American Robins cool off by submerging themselves in water and, similarly to winter time, fluff up their feathers, but more so this time in hopes of catching a breeze across their skin. Tufted Titmice follow similar adaptations, but also increase the frequency of feeding to keep their bodies warm in the winter.

Unlike American Robin and Tufted Titmouse, Black-capped Chickadees utilize facultative hypothermia to endure the winter months. Facultative hypothermia allows for birds to drop their metabolic rates at night so that energy is saved for when they need it. Black-Capped Chickadees' body temperature 18° F from 104° to 86° F. Also, BCCH that live at higher latitudes are much larger than those more southerly chickadees to allow for more fat to be on the body to store more heat. This is a clear example of a physiological (and regional) adaptation. Carolina Wren, on the other hand, lack this feature and utilize sheltered or indoor roosting sites to stay warm. They even share roost sites with other wrens.

The one true migrant observed was the Ring-billed Gull. RBGU breed north of Vermont near the Hudson Bay, and across the country in all southern provinces, as well as north-western states in the US. In the winter, east coast gulls migrate to the coast from Massachusetts south to the Caribbean. Those in Burlington most likely migrate to Massachusetts beaches for the winter and the St. Lawrence River and Gulf for spring breeding. Burlington has begun to warm for the spring, welcoming in migrants like the Ring-billed Gull. Lake Champlain having melted also probably facilitates the arrival of RBGU because they are coastal birds largely, or at least spend time on shores near water.

Posted on March 30, 2023 03:22 AM by