Field Observation 4 - Migration

Date: April 6, 2019
Location: Salmon Hole (44.4870° N, 73.1881° W)
Weather: about 47 degrees F, mostly cloudy, windy
Habitat: mixed hardwood trees (some maple, birch, cottonwood)
Other: one small tree had fallen since the last time I was there, almost all the snow and ice has melted, the pathways were very muddy
Arrived: 12:00 pm
Departed: 1:53 pm

Birds Observed:
• American Crow – saw one in a tree, and heard others calling
• American Robin – saw a group in a tree, and saw a different one foraging on the ground
• Canada Goose – saw two pairs at different sections along the Winooski River
• Common Merganser – saw a group near one pair of geese and by the gulls
• Double-created Cormorant – saw one foraging alone and then drying out its wings
• Eastern Phoebe – saw one hopping between the branches
• Hooded Merganser – saw a male and female floating in the Winooski
• Ring-billed Gull – saw a few by the pair of geese, much fewer than last time, might have been some Herring Gulls as well, some gulls were flying overhead
• Northern Cardinal – saw one female and heard another singing
• Song Sparrow – saw one on a fallen tree near a dead animal carcass (I think it was a deer), heard the sparrow calling

Birds Heard:
• Tufted Titmouse
• Black-capped Chickadee

Out of the birds I observed this time, there are five that are commonly year-round residents including American Crow, American Robin, Northern Cardinal, Black-capped Chickadee, and Tufted Titmouse. Crows and robins are short-distance migrators, but can reside in Vermont for the whole year. Both these species tend to roost in large flocks, which can help conserve heat and increase foraging capacity during winter when resources are scarcer. Northern Cardinals are able to survive very low temperatures, down to about -40oF by increasing their metabolic rates, decreasing water loss, and fluffing its feathers. In winter, Black-capped Chickadees eat a variety of foods including plant matter and sometimes fat or meat from frozen carcasses. Tufted Titmice prepare for winter by storing seeds in bark crevices and access them when other resources are harder to find.

One facultative migrant observed includes the Double-crested Cormorant. This species can be resident or a medium-distant migrant. Populations from the Gulf of Mexico often migrate to the great lakes area, arriving in early-April, and sometimes continue north to parts of Canada. They arrive right around when the ice cover has begun to melt, and there is open water exposed again. This is especially important because they mainly feed on aquatic vertebrates. Aside from water temperatures, in lecture, we also discussed the importance of the photoperiod and the sensitivity migrating bird have to this time. Migratory birds are sensitive to extended during of daylight, and in response, can tell when they should begin their migration.

Based on the ranges of the species I observed, none were obligative as they all had year-round ranges, which suggests they can be resident species in those areas. For an obligate migrant, I would expect to only see a wintering range or non-breeding ground, breeding range, and migratory range. Migrating and being one of the first migratory arrivals to a site means the individual can access those resources before later migrants. As more species arrive, resources start to run out again over time. However, arriving too early could be a challenge too if foods such as fruits or insects accessible or active at that time due to variations in that year’s season.

Sources
• Used both All About Birds website and Cornell’s Birds of North America website for more information about migration, physiology, and behavior of the species

Posted on April 8, 2019 07:02 PM by mwolpert