Field Observation 4: Migration

A group of my friends and I traveled out to the Intervale on April 6th. We walked along Calkin's Trail for most of the way were it was 40˚F and overcast, with 25mph winds.

We observed many year-round residents, like the Black-capped Chickadee and the Tufted Titmouse. These birds forego migration because it would not be beneficial for them in the long run. The amount of energy they expel during travel does not even out with the amount of food/energy they have to intake in order to make up for that lost energy. So since they have to eat so often, it wouldn't be the best idea for them to migrate. Since these birds do not migrate, they have adaptations put in place to survive the harsh winters. Some species can slow down their metabolism in order to use less energy while they are resting so they don't have to search for food all of the time (especially since there is little food around during the winter). Other species, like the Chickadee, can go into a state of hibernation and practically freeze (go into a hypothermic state) while remaining alive in order to conserve energy and wait out the cold spells that come with winter. During the fall, birds also stock up and start caching a good amount of food in their nests and in crevices in order to survive the winter.

A facultative species, like the Canada Goose or the Mallard, could have stayed here during the winter or if they chose to, they could migrate down south. Whether they choose one option or the other, they still have to migrate up north for the summer to breed. For both of these species, what determines their stay or migration is weather, availability of water, and abundance of resources. If it gets too cold or too warm for these birds, if every body water freezes over or some stay thawed, if there are a lot or little to no resources, then these birds will choose to stay or migrate. Some of these species, like in Burlington, are also just normally residents to their specific location, however birds of the same species in higher elevations, like Alaska, have to travel and migrate because it gets too cold and resources get too scarce (called the leap-frogging effect).

We saw two obligate migrant species, the Ring-billed Gull and the Common Merganser. The advantages of arriving early to Burlington is to get an early start on all of the seeds and food coming out by budding and sprouting plants, also to maybe get a lot of worms during the wet season. Another advantage maybe to get first pick on the location of their nest before mating season starts. However, a disadvantage like we saw this year, would be that sometimes the migrant species arrive too early and the Burlington cold and snowy weather hasn't let up yet. This means that the birds could get snowed in, and since they aren't used to the cold weather and snow, they might not be able to get a lot of food resources or stay warm enough to stay alive.

Mini Activity: The total possible miles traveled between Burlington (The Intervale) and all of these birds wintering locations is 17,631 miles.
Mallard: 2,418 miles
Song Sparrow: 1,294 miles
Mourning Dove: 0 - 4,331 miles
Tufted Titmouse: 0 miles
Black-capped Chickadee: 0 miles
American Goldfinch: 1,601 miles
Northern Cardinal: 0 miles
Common Merganser: 706 miles
Wood Duck: 2,233 miles
American Crow: 0 miles
Canada Goose: 2,306 miles
American Robin: 0 - 2,742 miles

Posted on April 9, 2019 02:05 AM by elizabethkaufmann