Field Observation: Ecological Physiology

For this week’s field journal assignment, I travelled over to Centennial Woods on Tuesday, March 3rd. I arrived at my birding site at about 1:00 p.m., and the habitat at my site consisted mainly of deciduous trees with a few conifers scattered throughout. There was also a small stream nearby, and I sat on a slight incline. I positioned myself slightly off the trail facing a relatively dense stand of trees. The stream I mentioned before was nearby on the bottom of the hill that I was on, but far enough away that the sound of the water was not noticeable. The temperature was about 50˚ F, the sky was mostly cloudy with some short periods of sunlight, and the wind was minimal overall. As soon as I reached this spot in Centennial Woods, I began to hear a variety of songs and knew it would be a good place to see some birds.

Although nearing the end of winter, it is not yet spring. It is becoming increasingly more evident that spring is near, however. The species I observed on my recent birding trip to Centennial Woods included the Black-capped Chickadee, American Crow, Herring Gull, White-breasted Nuthatch, Tufted Titmouse, Northern Cardinal, and a Downy Woodpecker. A lot of these species will store extra food to provide more energy for warmth. Another advantage is evident in species such as the Black-capped Chickadee, which have insulating feathers, and this allows them to stay in Vermont all winter. Northern Cardinals, for example, will often stay in pairs and take shelter in coniferous trees during the winter. Crows actually use the mechanism of torpor that was discussed in class, which is basically an extreme form of hypothermia. Shivering is used by most of the species as a method to generate heat. Most of these species, the White-breasted Nuthatches included, store extra fat on their bodies over the winter months to aid in winter survival. The fat reserves they build up provide insulation and energy storage.

As for how the birds budget their time in the winter, it is common for many of the species to be slightly less active than they are in warmer months. The Black-capped Chickadees I observed seemed quite active, however, and this could have to do with the uncharacteristically warm temperatures for this time of year. They fluttered from tree to tree and were also quite vocal. I did get to see a Downy Woodpecker feeding as it pecked into the side of a large tree. This bird was hunting for insects in the wood, and it repeatedly pecks its beak into the bark in search of them. Overall, most of these species will find shelter to spend most of their time in when the temperatures drop. They store fat so that they are able to spend less time searching for food in the winter as well. Other species, such as the American Crow, were most likely hunting for scraps of food or anything they could find. Since I only saw them flying overhead, they likely spend most of their time in the urban areas of Burlington, where there are plenty of things for them to scavenge. The songbird species (Black-capped Chickadee, Northern Cardinal, Tufted Titmouse, White-breasted Nuthatch) mostly eat seeds, nuts, and berries. These can be harder to find in the winter with a lot of snow coverage, which is another reason why fat reserves are so crucial for survival. Their diet will be different in the winter than other months simply because of availability of resources. The Downy Woodpecker, for example, may have to switch to eating seeds or nuts when it gets especially cold because insects will be less prevalent. As for sleeping, most of the songbird species I observed would utilize cavities in the hardwood trees. This is especially true in winter because the birds will look for shelter that also provides warmth. The Herring Gull that I saw briefly as it flew overheard, however, would likely sleep in flocks near a water source. Most birds would overnight in holes and snags during the winter, for protection from danger and the cold temperatures.

At my birding site, I noticed a few dead trees with these cavities in them. I had seen these while walking through the woods before, but I was not aware of their purpose. Although I didn’t go to my site quite at dusk, I definitely noticed a correlation between snag and bird abundance. As I walked to the site, I did not pass many dead trees and a lot of the trail was relatively open, with scattered conifers and ground shrubbery. However, once I reached a denser stand of trees, including a good number of snags, the bird songs immediately became more abundant. I examined a handful of these snags more closely, and most of the cavities in them were quite small. This did not surprise me considering the most abundant species at this site, by far, was the Black-capped Chickadee. For the most part, the snags that were on the smaller side also had cavities that were small as well. I did see a few larger snags that had relatively large cavities, which would obviously shelter a more substantial bird. Snags are very important for wildlife year-round. A lot of small mammals (squirrels, chipmunks, etc.) will use these trees as a home, and this is also true for some of the bird species in Centennial Woods. The Downy Woodpecker I saw may also search these snags for insects, meaning they provide a source food to some wildlife species. For the most part, however, the snags are important to an ecosystem because they provide a great habitat for wildlife. This is especially important in the winter months, when bird and mammal species are desperate for warmth and shelter from the cold.

Publicado el marzo 4, 2020 08:43 TARDE por bethanysmith512