acshiers's Journal

Field Journal 3: Ecological Physiology
March 8, 2021
Start time: 9:03
End time: 10:42
Location: Centennial Woods, Burlington, VT
Weather: 19 degrees F, 10-20% cloud cover, NNW wind at 3 mph
Habitats: forested areas, including pine, deciduous, and border near aquatic habitat

Birds, at the moment, are trying to limit the amount of energy being spent in response to the limited availability of food. In order to do this, their activity will be reduced. Resting and sleeping will increase, while behaviors such as singing, which is very energy consuming, will dramatically decrease. As the cold temperatures and harsh weather conditions make survival difficult for many organisms, birds must adapt their diet to allow them to take advantage of any available nutrients. Species such as White and Red-breasted Nuthatch will peck under the bark of trees in search of dormant insects overwintering. Robins were observed near crabapple trees, where they can feed on the dried fruits. Crossbills use their uniquely adapted beaks to pry open pine cones and access the seeds. Other species of birds utilize a caching technique. Black-capped Chickadees will quickly gather large amounts of seeds at one time, and store them away to access later. Species will utilize any human-given food sources as well, such as bird feeders and suet blocks that provide essential fats and energy to help get them through the winter.

In the harsh cold of winter, birds have a number of different behavioral and physiological mechanisms that are used to maintain a warm body temperature. In my own observations, I observed a behavioral technique, where a male Northern Cardinal had his feathers fluffed up to create extra air pockets. This action retains heat and creates an extra form of insulation for the bird. Some species of songbirds utilize the warmer, microhabitat found in tree cavities, and they often utilize huddling as well to shield from the elements and generate more trapped heat. Apteria are areas of a bird where no feathers grow, resulting in large quantities of heat to be lost from them. The most prominent ones we can observe are the feet. To keep these areas warm, some species will tuck their legs under their insulated wings, either from standing on one leg, or laying on their sternum.

Species such as Tufted Titmice and Black-capped Chickadees prefer to overnight inside the hollows made in snags. This allows for enhanced thermoregulation during harsh temperatures. Multiple individuals of these species will tend to huddle together within the cavities to increase the amount of heat generated. Dense vegetation also provides a welcoming area to overnight for many songbirds, providing them with some insulation, shelter, and protection from predators.

Mini activity:

Over the course of my experience I was able to identify a total of 14 snags near the trail through Centennial Woods. Each snag was primarily made from a once living White Pine tree, and contained anywhere from 3 to 18 cavities created by birds. It was seen that there were often more rounded, smaller cavities present in regards to only a few large rectangular ones. This illustrates that Downy or Hairy Woodpeckers may either be more present than Pileated Woodpeckers in the area, or that Pileated Woodpeckers rely on snags less than the other aforementioned species. There was also a distinctive relationship between snag size and cavity abundance. The smaller the size of the snag, the less cavities were present. This may likely be due to the time the snag has existed within the forest. Over time, the snag may have decomposed and disintegrated more, causing more insects to feed, and therefore an increased bird presence on that snag compared to a taller one. This trend was also observed in cavity size, where the cavities were larger in the short snags. This may similarly be as a result of time, or perhaps species presence. If these larger cavities were created solely by Pileated woodpeckers, we can note a relationship between smaller snag sizes and an increased Pileated Woodpecker preference. However, these larger cavities may be as a result of repeated use over time. Species such as squirrels and chickadees often enlarge cavities created by woodpeckers in an effort to access other parts of the snag or create a viable shelter for overnighting. This would be evident in the smaller snags as they are most likely a bit older than the others, allowing more time for cavities to be made and then widened in the future.

Tapping on any of the snags unfortunately did not result in any bird sightings from inside. However, during observations, a White-breasted Nuthatch was seen inside a natural cavity at the top of a snag produced from a decaying pine tree. It was seen rummaging through leaf matter, perhaps in search of insects for food. A Red-breasted Nuthatch was also observed on a broken branch protruding from a snag. It appeared to also be foraging for insects, but underneath bark instead. Although these individuals were not observed within the snag cavities themselves, it is important to reflect on how different species can benefit from the presence of snags and their variable functions. We can see that snags provide a welcoming shelter for many species looking to overnight and avoid harsh weather conditions and predators. These cavities can also serve as nesting locations for many songbirds as well during the breeding season. Black-capped Chickadees and Tufted Titmice are primary species that use snags for shelter, but sparrows, finches, and other small song birds also utilize these spaces for the same reason. As observed, snags can also provide a great habitat for insects, and therefore great food sources for many different species of birds. Holes present throughout all snags, both circular and rectangular, are clear evidence of woodpecker activity from a range of species. Both species of nuthatch were observed foraging along the surface of the snags as well, confirming the importance of snags as a potential food source. Other species within the ecosystem also benefit from snags, where squirrels will utilize woodpecker cavities, and the decaying wood will provide a habitat for many insects and fungal species.

Field Journal 4: Social Behavior and Phenology
March 21, 2021
Start time: 9:34
End time: 10:53
Location: Lake Champlain Waterfront, Burlington, VT
Weather: 35 degrees F, 0% cloud cover, SSE wind at 6 mph
Habitats: Lakeshore covering both shallow and open waters, urbanized habitat with sparse trees.

I took a few moments to observe a small group of four Mallards all floating on the lake and traveling in the same direction. in terms of interspecies interactions, it appeared that this species relied on visual cues or soft vocalizations directed between the group. One male would venture off and dabbled down for food. This behavior was observed by another female in the group, who proceeded to travel over to the male and feed there. The rest of the group then followed after visually observing this behavior. This interaction was different then when mallards were observed flying together, where loud vocalizations were heard. It was a bit difficult to discern what these vocalizations may mean, as the small group were only traveling in one direction with no observed physical interaction. However, it could be hypothesized that they were attempting to communicate the direction they wanted to fly, and were trying to keep each member of the group together. The loud volume of the vocalizations may also indicate that they wanted to make their presence known to other mallards in the area.

This interaction was quite different from those of other species, such as the Ring-billed Gull. I was able to observe an interspecies interaction. between two individuals swimming in the lake. There were no attempted interactions between the two. One proceeded to sit in the water looking around, while the other was much more active. It dipped its head into the water, perhaps to feed, and eventually took off flying from the water on its own. Vocalizations were made once in flight, perhaps to find other individuals or make its presence known. I was unable to observe any prominent interactions between two different species, however different vocalizations, such as alarm calls, may be understood between many different types of birds.

Looking at the plumage patterns of mergansers, we can see how the coloration provides a considerable ecological advantage for the species. The male, seen with dark iridescent black and green on its back and white on the underbelly and bottom wings, provides it with camouflage on the water. The darker back and head blends into the dark water surface as seen from a top view, protecting against potential predators The white along the wings may help break up the shape of the bird in rough waters. The white underbelly blends in with the light coloration of the sky as seen from below the surface of the water, helping the bird remain difficult to spot by prey. Females have a much more muted coloration of grey and whites on the body, and a brownish red head. This coloration may help the female camouflage more effectively than the male, allowing her a better chance of survival to protect any offspring or reproductive success of the species.

The plumage of house sparrows that were observed is quite different. Although they exhibit sexual dimorphism, both the male and female have very muted brown and grey plumage. This coloration may help this species camouflage within short shrubbery, bushes, and branches, which is different habitat compared to that of the mergansers. House sparrows also exhibit a slight form of counter shadowing, with underbellies being slightly lighter than the back of the bird, allowing for shadows to make the lighter bottom match the value of the top of the bird. This phenomenon is not as important for the mergansers who spend much of their time on the water, requiring a more stark contrast in coloration between the water and sky.

Returning to the observations of the four Mallards, particular observations were made of a male who explored the area dabbling for potential food underneath the water surface. It was swimming alongside two females and one other male, and proceeded to leave the group by a few feet and dabble, before returning back to the group. this behavior fits into circadian rhythm cycles in a few ways. During the day, metabolic processes increase, accounting for increased activity and feeding behavior. This light provided from the sun has caused the Mallard to be more active and alert, as the pineal gland receives the light and the hypothalamus regulates all metabolic activity through neurotransmitters. When looking at circannual cycles, it can be observed that this Mallard would be in the process of vernal spring migrations to reach breeding grounds. This would require high energy to complete this activity efficiently.

Mini Activity -
Spishing attracts birds for a number of different reasons, and can be really effective at drawing birds out of hiding. It can be most productive in a fairly open area with vegetation that provides cover for different species. This sound primarily attracts small birds, such as Black-capped Chickadees due to curiosity, and other species will often follow the smaller birds check out the situation. Another possibility for why spishing attracts birds is due to defense. The sounds may be interpreted as aggression, as it mimics alarm calls that are often made when a threat is nearby. This results in small birds to flocking together to investigate and drive off the potential threat. Although this method may be effective, it should be used sparingly as it promotes stress in different species. Although defense is the main hypothesis, spishing also resembles the sounds of many insects, potentially attracting insectivores to the area in search of a potential meal.