Field Journal Entry #4

Date: March 25, 2024
Start time: 15:39
End time: 16:48
Location: Centennial Woods Natural Area (44.475362, -73.188345)

Temperature: 40°F
Wind speed/direction: 8 mph SE
Precipitation: 0”
Habitat(s): mature conifer stands, mixed hardwoods, fields, streams and wetlands

Species List:
Black-capped Chickadee (Poecile atricapillus)
Ring-billed Gull (​​Larus delawarensis)

Today’s fieldwork took place in Centennial Woods to consider different wintering strategies of birds found in Burlington, specifically their choice to migrate or not. When walking to Centennial, I heard the sound of a gull flying overhead and, upon closer inspection, I determined it to be a Ring-billed Gull (​​Larus delawarensis). Ring-billed Gulls are not resident species in Vermont and are considered obligate migrates due to the fact that they leave each year at around the same time, as if they are “hardwired” to do so despite outside influences such as a lack of food availability. Even if their food sources were available in winter, they would still be expected to migrate. This makes sense for Ring-billed Gulls because they are omnivores and eat bugs as a main part of their diet which would go away in winter and can be found more south and come back around April. As I entered Centennial Woods, I encountered a group of Black-capped chickadees (Poecile atricapillus). As usual, they were foraging in the brush and shrubbery that can be found all over Centennial Woods. These birds have a quite the contrasting wintering strategy to the Ring-billed Gulls. They are resident birds which means they stay in Vermont all-year-round. In order to survive the harsh Vermont winters, Black-capped chickadees undergo facultative hypothermia which is where they are able to purposely shut down their bodies enough to where they stay alive while having their metabolism as slow as possible. This may be just as dangerous as migration because if a predator found them in this state, they would not be able to fight back and it takes several hours for them to be back to normal. Additionally, this is why tree cavities are very important to resident birds such as the Black-capped chickadee because they provide shelter.
Ring-billed gulls spend the winter months in the southern United States. If they are going all the way to the tip of Florida and back again, that would be about 3,450 miles round trip!

Publicado el marzo 25, 2024 10:29 TARDE por noxgiordano