Diario de ivdupont

My walk took place on April 24, 2019, from 5 to 6:30 and going from the Echo center up towards the defunct water treatment plant. The weather was chilly and overcast with intermittent light rain and drizzle throughout.
On my walk, there were two species of birds which I saw that were or may have been exhibiting behaviors relating to reproductive ecology. The first one was a pair of rock doves. Rock doves practice serial monogamy and mate for life. Individuals are capable of breeding at any time of year, because they can produce a specialized substance called ‘crop milk’ which is used to feed their infants. In colder temperatures, like we have in Vermont, the hatchlings spend a longer time in the nest in order to compensate for the temperature. I did not get much of a chance to observe the pair before the peregrine falcon I also saw swooped on them and they scattered, after which I did not see them again.

The second bird exhibiting behaviors which I believe were related to reproductive ecology was a male black-capped chickadee which was posturing and defending its territory in the small strip of trees up by the apartment building. I only saw the one bird, and I am not quite sure if its behavior was directed at me or another bird out of sight. Chickadee nesting season is from late April through June, so it makes reasonable sense for the display to be related to territorial or nesting defense.

Comparing nesting habits and needs, Chickadees nest in holes in trees, anywhere from 5’-20’ above the ground, that both sexes have helped to excavate. The female then lines the nest with soft material like hair or moss. The male feeds the female throughout, and often starts feeding her in the early spring. In contrast, the nest of the rock doves are found naturally in cliff ledges and in various artificial replacements in cities. These replacements can include the window ledges of tall buildings and rain gutters. In the case of these pigeons, I believe they were nesting in the supports of one of the piers. This would provide ample place and support for a nest of grass and twigs. They may even have used this nesting area more than once. Although I did not see nesting behavior from the peregrine falcon, and hunting behavior can take place over a much wider area, it might be possible for them to build nests on ledges of hilltops, bridges, and other structures. Otherwise, natural nests are mostly located in cliff ledges, with occasional hollows of trees or previously used snag nests. The male feeds the female, and they will defend the immediate area of the nest from intruders.

For my walk, I reprised the route from my first walk where I saw minimal birds to see if anything had changed along with thing beginning to warm. I went from ECHO, at the waterfront, down towards the Coast Guard station and the defunct water treatment plant. The time was from 2:30 to 3:30, the temperature was about 45 degrees or so, and the weather was overcast with a high ceiling.

Most of the birds that I saw on my walk are resident, not migratory. One of the year-round resident species that I observed during my walk was the House Sparrow, which is an incredibly wide-spread species not just in the state of Vermont but in the United States as a whole. One of the most important behavioral adaptations that allow house sparrows to survive in such a wide range of environments and climates is their interdependence with humans. House sparrows predominantly eat seeds, but they are also highly adaptive in their food-finding behaviors and even the range of food they can eat- according to the Audobon Society, they can even digest starchy grains like those found in bread. In winter, they can subsist on birdfeeders and even food that they scavenge.

In contrast to the house sparrows, the American Robin is a migratory bird with occasional overwintering flocks depending on the presence of food resources. Their migration is motivated by the presence of food as opposed to temperature- berries in the fall and insects and earthworms in the spring. The number of overwintering birds can change from year to year, especially in northern areas like Vermont.
The robin I saw may have been overwintering locally, or it might have been migrating back from its winter range. Something that might have changed in the environment to facilitate its arrival in Burlington would be the availability of food. Now that temperatures are warming and the snow is melting, there is more moist soil and probably the prevalence of bugs and earthworms is increasing, providing plenty of resources for the birds to use to eat.

For the mini activity, I have no way of knowing if this robin was overwintering in Burlington or if it had come from an overwintering location further south. According to Birds of North America, most Robins who breed in Canada and the Northern US, like Vermont, tend to overwinter in the southern U.S and Mexico. The average distance for a robin to migrate is about 500–1200 km. If I assume that this bird came in a straight line from Florida, the furthest possible distance straight down, it would have travelled about 2384 km.

My walk took place on Wednesday March 13, 2019, from 4 PM to 5:45 PM. The habitat around the trail was primarily loose shad, with bittersweet vines and green briar thickets providing intermittent patches of dense cover. The weather was overcast, with no precipitation, and the temperature was about 4 degrees Celsius/40 degrees Fahrenheit.

One of the first things that I noticed while heading down the trail was that right on the other side of the tree line of shad and brambles was an apartment complex with several well-stocked bird feeders. There was a group of multiple male and female house sparrows, some red-winged blackbirds, and at least one blue jay going back and forth from those bird feeders to the tree line. The house sparrows in particular were calling back and forth and vocalizing loudly in general. They seemed to be living in the stands of shad instead of simply visiting for the use of the bird feeders, like the red-winged blackbirds.
It was hard for me to tell whether there was simply one group of house sparrows moving around within a single territory, or more than one groups who were living close to one another with distinct spaces of their own. It probably would have been easier to tell if I wasn’t so close to them directly. In addition to their usual ‘chirp’ calls, I also heard some sharper calls that may have been alarm calls. These sounded more like ‘cheer’ and were a bit louder than the usual chirping calls.

I heard the downy woodpecker before I saw it, as it was drumming on wood to forage for food. When you compare the plumage of the woodpecker to one of the male house sparrows I saw, there’s a marked difference. The house sparrow is not brightly colored, although it has a distinct ‘bib’ marking of darker feathers under its beak that makes it easy to recognize. This makes it easier for these sparrows to camouflage themselves in the denser foliage. On the other hand, the woodpecker’s contrasting black and white plumage serves to break up its outline and can provide useful in thermoregulation.

Lastly, I chose to focus on one of the red-winged blackbirds to study individual behavior. It was going back and forth from the bird feeder to a single shad on the edge of the field and then back again. Since red-winged blackbirds are a short-distance migratory species and are just starting to come back to the island after the winter, it probably appreciated the bird feeders as a source of food, especially since the weather until then had been unseasonably cold from what they were likely used to.

The mini-challenge was mostly unsuccessful at attracting birds, as no matter the timber or pitch of my pishing it scared the house sparrows off. There would be a lot of alarm calls and then it would take a while for them to go back to what they were doing and release their guard again. I think that birds react to this call - and in different manners depending on the bird and the pitch and timbre of the call - because it resembles calls of their own, whether a positive identification or closer to a warning call. It would also be interesting to see if different birds reacted differently to the same noise in different pitches.

The time when I started my observation walk was 4:30 PM on Tuesday, March 12, 2019. The weather was sunny with no clouds and very warm for the season at approximately 5 degrees Celsius / 41 degrees . I began my observation walk by heading up Clayhead Trail to a clearing with prominent snags and dead trees at the edge of a mowed field in order to complete the mini activity.

There were approximately five snags in total, located at the south-western edge of the clearing. I did not see any birds when I approached the trees, nor when I knocked on a few of them with my walking stick. However, I did see that several of the snags had cavities of varying sizes, including a hollow trunk with fresh feces around the bottom. Snags have varying uses for different species of birds, but each use is essential in its own way. A snag can provide cavities for nesting and shelter, insects to forage, a place to perch while hunting, and a place for food storage. Some of the birds which utilize snags and can be found on Block Island include various species of woodpeckers, who utilize them as a source of food, Blue Jays, who may use them to store food, and Black-capped Chickadees, who use cavities as winter shelter and nesting.

I didn’t see many birds on the Clayhead Trail, although I heard many calls including both the crow and alarm calls of the male ring-necked pheasant. I’m not sure why I didn’t see more birds directly, although I think it might be because of how warm it was and where the trail was located. Since it ran through a mowed field, the birds that I had heard were probably foraging off in the dense shad and underbrush where there was more winter food to be had. Going back up Corn Neck Road towards Sachem Pond, I had more luck. In the pond itself was a group of Whistling Swans, eight in total in four pairs. Some of them were sleeping with their heads under their wings while floating on the water, and some of them were dabbling for food. Since Sachem Pond is brackish, it rarely freezes over in the winter, and was probably attractive to them as a source of the water plants that they eat. The last notable bird that I saw was a male Red-winged Blackbird sitting on the top of a phragmite plant that was just strong enough to support his weight, and he had his feathers up on end as another adaptation to beat the winter temperature. This provides an added layer of thermal protection from the cold wind.

The time when I started my walk was 2 PM on February seventeenth, 2019. The weather was sunny with no clouds, and quite cold at 19 degrees. I was at the waterfront and headed up towards the “Urban reserve” between the skate park and North Beach. The habitat where I walked was mostly park with light tree cover which grew somewhat thicker up the hill to my right. I did not see many birds at all overall during my walk. I think that the temperature probably influenced the lack of birds, as well as the snow on the ground. I would probably choose to come back to the waterfront when it was warmer out and there was no more snow in order to see more birds. As I came down College Street towards the waterfront, I saw at least ten individual Rock Doves on the roof of the Echo Leahy center. They were displaying some behavior I found interesting – they would land on the roof, sit there for a little while, and then either one or two or a small group would take off again and circle before they landed on the roof again. If I were to use flight patterns to identify rock doves, I would take note of the distinctive sound that they make upon takeoff, almost a whistle, as well as their profile in flight and how they clump together in groups. The second bird that I saw, albeit briefly, was a single Black-capped Chickadee across the trail I was walking on by a bank of houses or apartment buildings. I heard a call first, and then I saw it fly from one tree to the other. When I crossed the path to get a better look, it flew up and behind the houses, and I didn’t see it again. Compared to the rock doves, the chickadee is much smaller and had a slightly up-and-down motion in flight.