Ecological Physiology

Time- 1:15-2:45
Date- 3/5/2020
Location- East Woods Natural Area South Burlington, VT
Weather- 43 Fahrenheit, sunny, no wind
Habitat- Northern Hardwood Mature Forest and forest-edge

This observation proved challenging. Being one of the first warm days of the year so far, it was difficult to observe birds in their natural wintering stages. I also ran into issues with actually making observations, despite the almost ever present chorus of calls. Specifically, I could hear Black-capped Chickadees everywhere that an Eastern Hemlock stand was present, but not see them. It was then that I slowed down to realize they were much more active then previous weeks, darting around the tops of trees as opposed to hanging near the bottom. Their transition from the bottom to tops of trees with warmer weather may be an indicator that Black-capped Chickadees spend most of their time at the base of trees to shield themselves from cold winter winds; once it warms there is no need for protection so they can begin foraging at the tops of trees. I observed two Chickadees slightly pecking away at branches which I believe was them foraging for insects in the bark. Additionally, the fact that their calls were only heard in Eastern Hemlock stands reveals that Black-capped Chickadees prefer to perch in conifers during winter, presumably because the needles provide warmth while the barren branches of a deciduous tree do not; I found four nests in Eastern Hemlocks but none in any deciduous tree. Moreover, I did not observe any chickadees resting at any points further supporting that birds are beginning their spring routines.

Black-capped Chickadees were not the only species displaying sings of a changing season. The Red-tailed hawk I observed was gliding in circles in the air, a behavior I believe to be hunting (unfortunately I couldn't get a picture because the branches in the air were too thick to see through with a camera.) The fact that he was flying in the air to hunt as opposed to perching and swooping is most likely explained by the high number of song birds in the surrounding tree tops. The hawk needs to fly up to get a better line of sight on the prey; Had it been later in the year it would most likely be hunting for small mammals with the perch and swoop method (Audubon Guide to North American Birds). The Hairy Woodpecker was particularly active, vigorously jumping from tree to tree in search of food. Hairy Woodpeckers pair-up with a mate in midwinter and use the females territory to build a cavity nest together. The fact that the individual I observed was a lone female hoping from tree to tree indicates that she was feeding as opposed to nesting. Had she been nesting there would be a male present and she would have spent more time pecking at one tree as opposed to taking a few pecks per tree.

Though I got to observe species i rarely see at home (hawks and woodpeckers aren't too common in the urban wasteland that is Long Island), the most interesting and surprising thing to me was the lack of snags, especially considering that East Woods is a mature forest. However, the sparse snags definitely displayed a pattern. Tall skinny snags tended to have a larger cavity close to the top, with smaller cavities running down. Short skinny trees tended to have a larger cavity closer to the base of the trunk, with few or no cavities above it. Though I do not know which species made these cavities, I would presume the cavities on smaller trees belong to a species that is very territorial and spends most of its time close to the ground. The cavities in taller trees are most likely made by a species that can tolerate, and possibly collaborate with each other for feeding and defense. The thick, coppiced trees, on the other hand, had virtually zero cavities on all observed individuals. The few cavities that were found were on the thinner, outer "trunk" of the coppiced tree. The avoidance to cavity in coppiced trees most likely exists because their thick trunks make it challenging, even for the heartiest of woodpeckers.

Publicado el 05 de marzo de 2020 a las 09:39 PM por benjaminrosen