Sam Christopher, Field Observation 2: Ecological Physiology

My birding excursion took place on March 3, 2019, from 7:15- 8:45 am at the UVM barn and surrounding areas including the nearby fields, Spear Street bike path, and the Burlington Country Club. The temperature was 22°F with a cloud cover of approximately 40% at the start, while the temperature warmed up to 25°F at the end with a cloud cover of nearly 80%.
There was a lot of bird activity at the UVM barn. Throughout the property there were European Starlings, Rock Pigeons, and House Sparrows. These species were possibly utilizing human presence as a winter adaptation. There are many feeding and shelter opportunities in this area. The House Sparrows were typically seen within the barns in the rafters or on the ground eating the cows’ food. The barn offers both an ample food source and protection from the wind and cold weather. The House Sparrows were extremely active and rarely stopped moving. Possibly the surplus food gives them enough energy to thermoregulate and maintain their body processes in the winter as compared to other species that utilize tactics like torpor.
The European Starlings and Rock Pigeons utilized other tactics to spare their energy in the winter. Both species were always seen in groups. The European Starlings tended to flock to the upper branches of trees while the Rock Pigeons lined the top of the barn. Possibly these species choose high up locations to capture more sun when it appears from behind the clouds. Being at the top of structures would allow them to obtain as much heat from the sun with little obstruction from other objects. The grouping of Rock Pigeons in a line may be another heat saving tactic. Huddling conserves body heat and may help individuals maintain their energy. Also, roosting in a line may help block wind from a few sides which can also decrease the amount of energy individuals spend on thermoregulation. Another tactic seen in the huddled Rock Pigeons is the fluffing of their feathers to limit their body heat loss. Positioning their feathers like this traps air among the feathers and ultimately keeps the individual warmer.
On the nearby bike path, there were less human structures and the habitat consisted of open fields and sparse tree coverage. There was a noticeable shift in presence of birds when the sun was covered by clouds and when it wasn’t. When there was no sun, there were no birds calling and no activity observed in the trees; however, as soon as the sun emerged multiple bird calls could be heard including a Northern Cardinal, Black-capped Chickadees, a Tufted Titmouse, and another unknown species. This was a drastic increase in activity compared to when the sun was clouded over. Possibly these species are more active in the presence of the sun since it will keep them warmer and cause them to expend less energy on thermoregulation. Two Black-capped Chickadees were observed foraging on a tree when the sun came out. From my observations, it appears that birds typically aren’t spending energy on breeding or high energy activities. They tend to use small amounts of energy to forage in good weather conditions, but mainly rest and save their energy in cold and sunless conditions. Limited energy use could also be due to limited food choices. During the winter birds have to rely on seeds or things that they cached throughout the year. In other seasons insects, berries, and other food sources may be more abundant which allows birds to obtain more energy, spend less time foraging, and more time exhibiting other behaviors including breeding or molting.
Mini Activity- Snag Watch:
Along the bike path and within the Burlington Country Club golf course there were a few snags and cavities in the trees lining the road. Many of the snags seen had at least one or two small cavities among the dead branches. Although I tapped on a few of the snags, no wildlife appeared. I can imagine that cavities are a useful habitat for wintering species as they provide habitat and protection from the cold weather and wind. Maybe cavities are utilized more at different times of the day. My birding expedition took place early in the morning. Perhaps birding in the afternoon or closer to dusk would have brought more results and observations of species near the snags and cavities. Two Black-capped Chickadees were observed moving around on a snag. One of these individuals kept returning to a cavity that was located on the snag. Possibly there was food cached there and this individual was foraging. Snags and cavities appear to be important in the winter as both a location to rest and to find food. Possibly smaller birds that winter in cold areas including woodpeckers, black-capped chickadees, and others utilize cavities the most.

Publicado el marzo 6, 2019 10:06 TARDE por sgchrist