Field Observation: Ecological Physiology
On March 3, 2020 from 12:30pm to 2:00pm, I walked a friend's dog around the edge of their property in Shelburne. When I first went outside, the sun was out and shining, and it was about ~34 degrees with little wind. Throughout my time birdwatching, the sun slowly began to go away and the sky was very overcast. The property consists of the house, driveway, yard, and a piece of farm land that I am guessing is used for corn in the summer months. Altogether, the property is probably about 2 acres big. The edge of the driveway and the yard is lined with different trees, including pine trees, tall and bare trees, and trees with berries on them.
At 12:30, I saw four American Robins hopping around on trees around the house. They were on trees that had little red berries hanging off of them. Eating berries on these trees is a winter adaptation for these birds, because the ground is too hard for the robins to look for worms in the grass/dirt. When the ground softens up in the coming months, I think the robins will transition from the berries to the worms. The robins were splitting their time between resting and foraging for berries. I also think that since all the berry trees are surrounding the house (and these types of trees are typically found around developments), that the robins are using the houses and the landscaping as shelter to sleep at night. The houses provide good protection against wind, and the bushes and trees that are planted for landscaping also provide protection against weather and predators.
I also got really lucky when I was looking for birds in the trees around the house... I heard a knocking and I looked up to find a hairy woodpecker up in a branch. It was very high up, but the beak looked longer than the head, so I guessed that it was a hairy woodpecker over a downy woodpecker. It also seemed small to me, which is why I didn't think it was a pileated woodpecker. I also did not see any red on the head, which led me to believe that it is a female. I am also not sure what kind of tree the woodpecker was in, but it looked like she was looking for food. I know that insects often lay their larvae in trees, so maybe the woodpecker was drilling for larva and pupa to feed on? This also seems like a winter adaptation because there are no insects out and about in the winter in VT, so the woodpeckers must adjust their diet and go for larvae that is alive and protected in the winter. After doing some research post-bird watching, I found that hairy woodpeckers prefer to eat beetles in the warmer temperature. So perhaps in the winter, they feed on beetle larvae rather than the adults to sustain themselves. This tree also had many holes in it, some of which seemed large enough for a bird to fit in. It could be that this woodpecker was foraging for larvae on the tree and also uses the bigger cavities to sleep in during the cold winter nights. The tree cavities could also serve as a sleeping quarter for other species of birds, although when I tapped on the tree no other birds seemed to be in the cavity. I watched the woodpecker for about 15 minutes, and it seemed like the woodpecker was solely using its time to forage/drill the tree. The weather was very nice at this point, so maybe the woodpecker was taking advantage and using this time to find food.
I ended up walking around for a while before seeing any birds. I think part of the reason for this was because I had a dog with me, who was off leash and may have deterred birds from flying in. Also, the large field may have also deterred birds since there is no shelter or hiding spaces. The next bird sighting occurred around 1:50, in which two American Crows were flying East after a hawk. I think the hawk was a red-tailed hawk, but it was somewhat difficult to see the red tail as there was a lot of movement in the sky. The crows were almost teaming up on the hawk, and it seemed like they were trying to chase it away. The hawk ended up flying further East and I lost sight of it, but the two crows remained in the sky. I think this territorial/aggressive behavior is definitely an unwanted expenditure of energy in the cold winter months, but perhaps the crows were chasing the hawk away from a food source? In that case, it makes sense that this was a necessary use of energy so that they could obtain food that is most likely scarce. I was also expecting to see a hawk since the property had a large field on it, and hawks would probably be able to search for rodents in the big open area. This would make hunting easier in the winter, since rodents are hard to scout out in denser areas and they are scarce to begin with in the winter.
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