Diario de haleyferrer

Date: March 6, 2019
Time: 2:00 - 3:45 pm
Location: Shelburne Bay
Weather: The weather on this bird walk was fairly cold, with temperatures dropping to about 10-12 degrees. There was a light snow falling for the majority of the time, with fairly consistent cloud coverage (blocking the sun).
Habitat: I walked through the forested area in Shelburne that is adjacent to the bay. While I started out traversing the trails, a lot of my exploring was done off of the path.

The species that I observed during my bird walk utilize various evolutionary and ecological tactics in order to stay warm and survive the Vermont winter season. Although I did not necessarily observe these behaviors and processes directly during my time at Shelburne Bay, there is an ample amount of research and studies that provides insight into these birds’ winter lifestyles.

During my walk, I saw a really large abundance of American Robins (at least ten were gathered in the first few trees upon entering the forest), which allowed me to undertake thorough observations and think a lot about their winter behaviors. I noticed that some of the stationary robins that were perched upon a branch seemed very large from where I was standing, at least relatively to the robins that I see in other times of the year. Upon investigating this observation after my bird walk, I found out that robins often will fluff their feathers to help retain body heat. I found that fluffing up feathers increases the air next to the body and thus offers more protection from the cold. The composition of the Robin’s feathers also plays an important role in their winter survival, as they have a dense layer of down feathers close to the skin, which trap air and act as an excellent insulator. They have other layers which exist on top of this down feather coat, which further helps in separating the cold external air from the body heat that is being produced. During my time at Shelburne Bay, I witnessed two different robins eating small morsels of food (they looked to be some sort of berries). Consuming calories definitely assists in keeping the birds warm as it increases fat buildup as well as causes a rise in body temperature. While the other robins were not seen to be eating any food, they did seem to be moving around quite a bit- even when I was standing still and hidden. The robins kept sporadically flying between various trees, often moving as a group. Perhaps this movement was a foraging tactic, or maybe the intermittent movement helped them keep their body temperatures elevated. American Robins, like many other birds, also rely on each other for heat through roosting and cuddling. In very cold temperatures, Robins can stay close together to share body heat as well as seek protection from other weather factors (ie. snow, wind). While I did not see a lot of direct contact between the Robins that I observed, I did notice that there was a very large group of them which stayed in very close proximity the entire time I observed them- a behavior which I don’t often see when I observe a robin or robins.
During my time at Shelburne, I also saw a single Barred Owl perched on a tree very close to the edge of the forest. As I approached the owl, I noticed that I was able to get extremely close without him moving or fidgeting. As he stared me down from atop his branch, I wondered how owls are able to stay warm during the winter season- especially considering they are such independent birds. Much like Robins, I figure, Owls have a very particular feather composition that allows them to insulate their body heat effectively. Barred Owls, along with other members of the Strigiformes order, have a fluffy layer of feathers that extends all the way down to their legs and toes. They also have thick pads on their feet, which allow their extremities to remain warm during low temperatures. Due to the lack of wind that was present during the time at which I observed the owl, he was able to stand upon a tree branch that was relatively exposed to the conditions that traveled across the nearby field. I assume, however, that if wind and precipitation were especially strong, the owl would have seeked shelter behind an on-ground object or a denser, more internally-located tree.
Even though I did not directly observe or notice such behaviors, I know that there are other tactics which these birds most likely partake in to stay warm during the winter. The countercurrent exchange between birds’ body and legs, for example, allows for birds to deliver heated blood to their internal organs, and reduce blood flow to extremities without risking frostbite. Birds can also tuck their legs/feet into their feathers to shield bare skin from the cold. Many birds also have physiological responses to cold, such as shivering, entering a state of facultative hypothermia/torpor, etc. These types of physiological responses help birds to control metabolic rate and generate body heat strategically. Birds often enter a state of torpor or hypothermia at night, for example, as a method of conserving energy for an extended period of time. This involves reducing metabolism and shutting down certain systems so that less energy is required to maintain a proper amount of heat.
Because the Shelburne Bay park is such a densely forested area, I saw an abundance of snags that were distributed throughout my entire walk. By the time I was only a few minutes in, I had already counted well above ten snags/dead trees. I came across various types of dead trees, all of which could definitely be potential habitats to birds and other wildlife. Where the trail opens up right at the edge of the forest, there are several small dead trees that lay across the ground and form a jumbled mess of branches and brush. When I first spotted this scene, there were at least six American Robins that were seeking shelter in there. As I continued to walk, I found numerous snags that were standing up right. Most of these types of snags that I observed had various holes and cavities in them, either being naturally formed or formed from wildlife/birds. I noticed that the taller snags often times had several holes distributed up the length of the tree trunk at varying elevations. This, I assume, could be due to the same species of birds seeking different shelters or areas to forage for food. I also noticed that the thicker snags had larger holes that appeared to be more suitable to fit a bird or creature that is greater in volume. I knocked on a couple of these trees to see if any organism poked its head out, but I did not find any sign of life when I did this. Although I did not see any birds physically in the snags/cavities, these structures are very vital aspects of many birds’ lifestyles. Birds, and other small animals, can use snags for nests, foraging, roosting, and perching. Because of the dead/hollow nature of the trunk and branches, snags are excellent resources for birds to excavate and create fairly intricate forms of shelter. Snags also are home to many sources of food that are consumed by birds, including insects. Perhaps I would have seen more activity around the snags and cavities if I visited the area at a time in which birds were awakening or settling down for the night (dawn or dusk), which I will keep in mind for my next outing.

Time: 12:00-1:30
Date: March 25, 2019
Location: Centennial Woods
Weather: Sunny, clear skies, 40 degrees
Habitat: Deciduous forest, trail running through, river and swampy areas create break in dense vegetation

note: my phone suddenly stopped working about halfway through the bird walk, so I recorded species by hand and tried to describe their relative location in the woods

Because my phone stopped working pretty prematurely on this bird walk, I was not able to record the exact location of every single individual I saw. However, I used that malfunction as an excuse to really slow down and spend more time observing how the various species of birds interact (rather than trying to record as many as possible on the app). When I took the time analyze the different sounds and behaviors of different birds, I was able to recognize some communication patterns across certain species.

Black-capped Chickadees were by far the most abundant species that I observed during my walk, and I was constantly hearing both their songs and calls as I traversed the forest. I noticed that when I heard a Black-capped Chickadee call (i.e. the “chicka-dee-dee-dee”) in one location, it was often followed by a different individual making the same call. I figured that this occurred due to the fact that a call signals some sort of danger or alarm, therefore it makes sense for other nearby individuals to respond and vocalize their recognition of said stimulus. The sing-songy “here petey” sound, on the other hand, seemed to be more randomly dispersed and less frequent. This is perhaps due to the fact that males are often the ones to sing for purposes of attracting mates, therefore it may not be as much as a call-and-response type of vocalization. In terms of visual behavior, the clusters of Black-capped Chickadees that I observed would often jump around the branches of a specific tree (perhaps foraging for food) and would often jump towards each other before spreading apart again. This type of behavioral interaction could perhaps indicate some sort of communication regarding the presence of a food source, or could be some sort of communication between a breeding pair (male and female).

Another species that I observed to be (potentially) communicating during my walk was the White-breasted Nuthatch. Much like the chickadees, I heard several nuthatch calls that came from individuals in different locations. The most common nuthatch sounds I heard were the “wha wha wha wha” songs as well as the raspy and more abrupt “yank” calls. I heard the song less frequently throughout the my walk, however I did hear it on multiple occasions in which it was carried out for an extended period of time. From what I know about White-breasted Nuthatches, their songs are used to find suitable mates for the upcoming breeding season (beginning in April, usually), therefore hearing this infrequent song makes sense. The “yank” calls were somewhat more frequent, and I presumed to have more of a two-way communicative purpose. During this time of year, monogamous pairs of White-breasted Nuthatches are most likely building their nests as well as foraging for food, therefore the “yank” or “yink” sounds that I heard were most likely signaling to each other a certain source of food or perhaps protecting the nest.

I saw a couple of American Robins during my walk, and heard several “cuck” calls as well as songs (“cheerio-cheeri-ie”). When I observed the robins, I heard these different sounds given in the same time period by the same individual(s). For this reason, I assume that both the song and call may work together to form similar purposes. For example, both the song and the call could be used as a signal of defending territory from potential trespassers, therefore it makes sense to hear them both in the same vocalization.

There were several species that I could not observe interactions for due to their more independent presence and lack of interaction with other birds of their kind. These birds include Pileated Woodpecker, American Crow, and Mourning Dove. I heard and observed all three of these species, however I only saw one individual of each throughout my walk. The American Crow was flying overhead above the forest, and gave out a few “caws”- which I assume was made to communicate with nearby crows that I did not see (because the call is fairly loud). The Mourning Dove that I observed was singing its beautiful “ooo-OOOH,- ooh-ooh-ooh” song from atop a very high perch. I presume this was a lonesome male that was singing this song for the purpose of finding a mate. The pileated woodpecker did not make any audible calls, however was drumming on a tree for an extended period of time- therefore I could not make out any specific type of communication/interaction.

During my walk, I spent time looking at the plumages of the Black-capped Chickadee and the Pileated Woodpecker, as I was able to get a pretty constant view of both of them. They are similar in that the main bodies of both of these birds have black and white feathered areas that are very contrasted and take on quite distinguishable patterns. They both have stark black and white stripes that begin on their head and may extend downward onto their body. One of the main differences between these birds’ feathers is obviously the bright red crest that exists atop the head of the Pileated Woodpecker. While this crest does not seem very practical for the purpose of blending into surroundings or keeping a low profile, it is heavily used in courtship displayed and as mechanisms of attracting mates. Evolutionary, it makes sense that more successful woodpeckers are those with brighter and larger crests that are more effective at attracting a breeding partner. Because the Black-capped Chickadee does not have any sort of vibrant distinguishing feature (nor any huge visual differences between males and females) it makes sense that these birds rely on other behaviors for courtship (i.e. buffing feathers or singing their song).

In terms of behavior of the birds which I observed, I found the Black-capped Chickadee and the American Robin to have interesting behaviors (which were fairly distinct from each other). Every time I saw a Black-capped Chickadee it was moving about- usually hopping on branches or taking quite flights around a tree. The birds were usually faced inward to the tree, suggesting that they were moving about in order to forage for food from the surface of the various branches or trunk. The dynamic nature of the chickadees suggests that their circadian rhythm is one that heavily surrounds foraging and eating throughout time spent awake.

The American Robin(s) that I observed, on the other hand, which much more composed and stationary than the chickadees. They were found on a tree towards the edge of a dense patch of vegetation, in a spot in which sunlight was directly hitting them. While they would give out a call/song, they did not seem to move too much. This could be because their circadian rhythm does not require them to be foraging/eating for a large part of their day, but rather it is more energy-efficient and preferred for them to be resting upon a perch and sunbathing.

“Pishing” Activity

There are many reasons why “pishing” can be used to attract or signal small birds. Although the “pshh” sound does not necessarily mimic the song of small perching birds, the raspy and abrupt nature of this sound can be very similar to some of their calls. Many small birds, such as the Black-capped Chickadee and the Tufted Titmouse, give shorter raspier calls that are used to signal alarm or distress, usually in the presence of some sort of predator. When hearing this call, small birds often will flock together to either chase away or find safety from a predator. Thus, if a similar call is made by a human, small birds may be enticed to flock towards this sound. Another reason why small birds may be attracted to this sound is perhaps the soft and raspy “pshh” sound is similar to the sounds and pitches created by potential prey, specifically smaller insects. Of course, there is also the possibility that the specific “pish” sound that is created by humans does not quite mimic any sound that the small birds are accustomed to hearing. In this case, it seems quite possible that the sound could attract birds out of their mere curiosity of this foreign sound.