Migration-Centennial Woods
Meghan Murphy
The birding excursion began at 9:22am on April 7th. It was an overcast day with little to no wind, and it remained overcast until the very end of our excursion. The temperature was about 35°F. There were two other people present, one of whom was Kayley Dillon. Our observations will be the same, but all other work was done independently. Starting at the main entrance of Centennial Woods, we immediately saw an American Robin and Ring-billed Gull. We continued walking until we came to the first board walk, where we stopped to look for the Black-capped Chickadees we had been hearing. This was a reedy, wet area with a few Eastern white pines closer to the trail. We were able to see two Northern Cardinals, a male and a female, and see several Black-capped Chickadees. A few more chickadees were called in by whistling their call and making them curious enough to come closer. At least two Song Sparrows called back and forth but could not get a visual on them. A Ring-billed Gull and American Crow flew over us while we were observing in this area. We continued until we came to the top of a hill dominated by Eastern white pines and scattered snags. We were attracted to the sound of woodpecker drumming and were able to see a Downy Woodpecker on one of the snags. A Pileated Woodpecker called farther in the woods, and another American Crow flew overhead.
After going back on the trail, we stopped on the edge to investigate an area dense with reeds. We were able to see multiple Black-capped Chickadees, and hear several American Goldfinches, and Song Sparrows. We heard a call that we initially did not recognize and saw what we thought might be a House Finch or Purple Finch. Later investigation strongly suggested that it was actually a Pine Siskin. A Downy Woodpecker called nearby. We continued down the hill and went off the trail in pursuit of the sounds of Song Sparrows. We went to a clear area scattered with reeds and a stream cutting through it. We wandered this area and could hear multiple Blue Jays in the forested area straight ahead of us. We saw several American Robins and heard Tufted Titmice, Northern Cardinals, and White Breasted Nuthatches and a Downy Woodpecker at various points throughout the surrounding forest. Two Song Sparrows finally became visible, perching in the reeds before flying away to the tops of trees farther in the forest. Two Canada Geese flew low overhead in this area.
After returning to the trail, we continued up a hill and moved down towards the board walk leading to the retention pond where we had heard the calls of male Red-winged Blackbirds. We stopped on the board walk and heard a White-throated Sparrow and Song Sparrows. We continued up the hill that overlooks the retention pond and could see a proud male Red-winged Blackbird calling and spreading his wings, fluffing out the red patches of its namesake. We observed him and a few others before continuing to the top of the hill where we heard an Eastern Phoebe. Turning around and continuing the way we came, we saw another Song Sparrow and several more Black-capped Chickadees. We came out of the same entrance we had started in and made our way down to the fenced pond near the road to see more Red-winged Blackbirds. We heard both a Mourning Dove and a Common Raven on our way to this pond, and after the Red-winged Blackbirds flew away, we ended our excursion at 12:02pm.
Some year-round species we observed were Northern Cardinals and Black-capped Chickadees. Species such as these can afford to forego migration to retain the energy that would be spent migrating and have various adaptations that allow them to survive Vermont year-round. Black-capped Chickadees are able to survive the Vermont winters by creating food caches that they can visit throughout the winter and by selecting cavities to spend the night in. These wee birds are also able to fluff out their feathers to retain body heat. At night, Black-capped Chickadees can enter a hypothermic state to conserve energy that would be used to try and keep warm. Northern Cardinals are also able to fluff out their body feathers to retain heat. Their heavy bills allow them to access seeds protected by hard shells.
Red-winged Blackbirds are facultative migrants that are starting to arrive in Burlington. This species was coming from the warmer southern United States where it spent the winter away from Vermont. The fact that they remain in the United States means that these birds can tell when conditions are favorable to begin moving back towards their breeding grounds. Specifically, these favorable conditions were the warmer weather Burlington had been receiving.
If an obligate migrant arrived in Burlington in early April, it would potentially have earlier access to food resources and territory with limited competition. However, if the weather shifts back to intolerable conditions, the early bird may waste energy trying to deal with the suddenly harsh environment, leaving it unable to cope or weak when competition arrives.
Facultative Migrants:
Red-winged Blackbird: 500mi
Pine Siskin: Varies depending on irruptive year, but could potentially be close to 1000mi
Eastern Phoebe: 2000mi
Song Sparrow: 155mi
American Robin: 1500mi
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