3/24 College Street &amp; Waterfront

Today's bird walk began at 1:46 pm on campus near the Waterman Green. The sun was shining through the entire walk and the skies were clear, although there was a strong, cold wind. Most of the bird walk took place in the residential and waterfront areas of Burlington, so the habitat was pretty much that of a town, favoring birds who did not mind living near people and buildings.
The first bird we saw on our way down College street was an American Crow that we heard calling. About a block and a half further, we came across a flock of House Sparrows hopping through the branches of a row of dense shrubs. They were extremely vocal , chirping at each other as they moved through the shrub. We also heard a black-capped chickadee on the other side of the street, but we were unable to locate it visually.
We continued walking down to the waterfront. We didn't see or hear any other birds until we reached Church street, where we saw a large flock of Rock Pigeons flying over head. We caught up to the flock when we reached Echo, where we saw it join with a second flock already perching on the roof of the building. Circling in the air nearby were 4 Ring-billed Gulls that seemed to fly down the boardwalk, and then back to Echo in large, sweeping circles. We walked along the boardwalk for a while, but were disappointed to not see any waterfowl. We decided to turn back and head back up the hill toward campus.
Again, we didn't see or hear any birds until we neared the area where we saw the House Sparrows. A few feet away, we could hear a bird singing at the top of a tall spruce tree. We had a hard time trying to spot the individual, so we stayed and listened to the song to try and figure out whether it was another House Sparrow or House Finch. After a few more minutes, we heard a few distinctive notes that identified it as a House Finch. A few feet away, my friend waved us over to help ID a yellow-gray bird sitting in what appeared to be either a crab-apple tree or a hawthorn tree. Upon closer inspection, its distinctive coloring and crest identified it as a Cedar Waxwing. As we watched, about three other Cedar Waxwings flew to join the first in the tree branches. Also in the tree were about 4-5 American Robins, as well as two others nearby. A White-breasted Nuthatch also flew in and started hopping up and down the tree trunk and some of the thicker branches. Two European Starlings landed for a minute or so, then took off to some of the trees in the distance. Soon after, a flock of 15-20 House Finches crowded onto the branches. They were all very noisy, and seemed to be disturbing each other, as well as some of the other species in the tree. After a few minutes, they into the foliage of a large cedar hedge, and could be seen foraging on the ground at the base of the tree, as well as flitting through the branches. We walked over and decided to try "pishing" to them since we hadn't seen to many Black-capped Chickadees. The House Finches seemed to quiet down a little and maybe look at us, but they didn't respond very much beyond that.
We stayed and watched the birds in that tree for a long time, comparing the behavioral differences between the species. The American Robins did not seem to be foraging, and sat perched on the branches, watching us, the whole time we were there. One or two of the birds could fly and land near another robin, however they all seemed to prefer having a little space between them. The Cedar Waxwings, however, often followed in a similar path along which one of the others had already been, and didn't seem to mind being close together. The Cedar Waxwings were actively foraging, and we saw them swallow several berries whole. This behavior makes sense in terms of their circadian and circannual rhythms, because they are known to be active during the day, as well as dependent on fruit trees for food in the winter.
Seeing so many species of birds all perched on the same tree really highlighted their differences in plumage. The Cedar Waxwing, for example, had subtle but striking coloring, while the American Robin had a simple and bold pattern. It is possible, evolutionarily speaking, that the American Robin was able to develop much brighter coloration, because it is a much larger bird and therefore not as vulnerable to predation as the Cedar Waxwing. I imagine the Cedar Waxwing evolved such beautiful, if not obvious, coloration and plumage as a way of attracting mates, while maximizing camouflage to avoid predators.

Publicado el marzo 24, 2018 11:43 TARDE por