Journal archives for March 2019

March 8, 2019

Ecological Physiology

Date: Feb. 28, 2019
Time: 6:30-7:45 AM
Location: Forest behind Raven Ridge, Huntington, VT
Weather: Clear and sunny, around 12 degrees, no wind. 1.5 inches of fresh powder over old snowpack, about 9 inches deep.
Habitat: New growth softwood forest consisting of birches, maples, oaks, aspen, with a dense patch of mature hemlock. Backed by a steep rocky ridge with lots of staghorn sumac, close to a tiny stream and a nearby small neighborhood with cleared fields.

Early in the morning after a cold night with fresh snow, I noticed that many birds were not yet up and about. After an hour, I heard more activity than I did around 6:30am. This is likely due to the way that small birds conserve energy overnight by lowering their body temperature and metabolism. Once the sun comes up, ambient temperature begins to rise, making it easier for birds to move around with less energy expenditure going towards body heat.

I heard Black-capped Chickadees singing their territorial fee-bee songs once the air got warmer. I wonder if some of these individuals had just emerged from a nightly torpor. Up on the rocky ridge, I found several nooks and crannies in the ledge where I think some of them passed the night. In a few crevices, I found some scuff marks where the rock was worn, and a little plumulaceous feather along with a bit of defecation.

I was unable to visually observe any chickadees due to the dense hemlock canopy, but if I had seen them, I expect they would have been plump and puffed up against the cold instead of sleek and thin like they are in the summer. The Cornell Lab of Ornithology tells me their diet is mostly seeds and fruit in the winter, whereas in the summer their diet switches to 80% insects. With the songs coming from the Eastern Hemlock stand, I wonder if they were eating hemlock cones or picking hibernating bugs out from under the folds of bark. Chickadees only eat their food where they feel safe under cover, so they often carry their food to a hidden spot to eat it. When it's cold, it would benefit them to find a food source that also provides cover to minimize handling time and maximize profitability in terms of energy expenditure, so maybe that's why they were in the Eastern Hemlocks.

Over the course of my walk, I found 5 dead snags. 4 were about a foot in diameter, and varied in height from around 10-15 feet tall. These snags were deciduous, and had cavities the size of quarters or golf balls. I rapped on the trunks and pressed my ear against them, but heard and saw nothing. The last snag I saw was from a massive White Pine that was likely a pasture tree at one point (there is barbed wire in the area). The trunk was about three feet in diameter, with lots of short stumps of branches still attached. The trunk broke off about 12 feet up, and I don't know if it was hollow or solid inside. I didn't find any cavities in this one, maybe because the wood was much harder and not yet very decomposed.

Snags are very important for Black-capped Chickadees because their cavities provide insulated spaces for the tiny birds to spend the night. Without them, chickadees would likely freeze during the winter. Tree cavities are also important for chickadees in the summer, because they build their nests and raise their young inside them. Tree cavities provide year-round protection from predators and the elements for Black-capped Chickadees.

Posted on March 8, 2019 04:39 PM by zoey_november zoey_november | 7 observations | 0 comments | Leave a comment

March 15, 2019

Social Behavior and Phenology

Date: 3/13/19
Time: 10:00-11:30AM
Location: Raven Ridge, Huntington, VT
Weather: Warm, around 30 degrees and slightly overcast. Snow is about 20 inches deep in most places.
Habitat: Around the edge of a small neighborhood and a mature forest that was logged last winter.

I observed a couple of Hairy Woodpeckers for about 40 minutes. At first, I could only tag along behind them as they flew from tree to tree. They called frequently, which helped me locate them, but they were always in different trees. One time one of them landed in a tree where the other was, and the other took off immediately, without being pursued. I don't know if they were calling to each other or not, but they were doing the sharp short 'peek' call, not the long rattle/whinny. Finally one of them settled high in a large dead White Pine, where it foraged continuously for at least 15 minutes. It then rested on a branch for about 6 minutes. Overall, during the time I observed it, it spent about 30 minutes foraging, 10 minutes traveling, and 6 minutes resting.

I also observed several species in the area of a few trees at the edge of the yard near a feeder. There were about 5 Black-capped Chickadees, a White-breasted Nuthatch, a Brown Creeper, a Hairy Woodpecker, and a Tufted Titmouse. As far as I could tell, only the chickadees were making use of the feeder – the rest were foraging under bark or calling out territory. The chickadees had a ritual for approaching the feeder: first, they would fly in close to the top of a nearby tree or shrub. Then, they would hop lower down as they scouted out the scene. When they determined it was all right, they went to the feeder, and then returned to their spot in the nearby shrub to eat the seed. Then they would either return to the feeder or go back to the woods. One time, a chickadee tried to land on the feeder while another was already there, and it got chased off with a quick set of chatter and wingbeats.

I tried "pishing" for a while, with various lengths, pitches, and tones to my amateur calls. Felt pretty foolish, and didn't notice any behavioral effect in the nearby songbirds. If pishing does attract small birds, maybe it is because they think there is a small stream nearby that they can take a sip from. Some pishes also sound a bit like an alarm call that is similar across species, so maybe they are coming together to defend an individual against a perceived predator.

The Black-capped Chickadee has black, tan, and white plumage arranged in thick horizontal layers. With dark above and light beneath, it exhibits countershading that helps it blend into its surroundings. Since the little bird forages both high up and on the ground, this makes sense in terms of camouflage. The contrast of black and white on its head likely attracts potential mates. The Hairy Woodpecker is entirely black and white, except for a patch of red on the back of its head, which it can either accent or diminish depending on behavior. It's plumage is arranged in a checkered pattern of regular black and white horizontal stripes across its back. When it clings to a tree trunk or perches on a branch, it maintains an upright body posture, and blends in easily from all sides with the bark and dappled shadows. The red flair on its head can be used in communication, signaling, and courtship. Having a bright splash of color shows evolutionary fitness as it makes an animal more vulnerable to being spotted by predators. Both the Hairy Woodpecker and the Black-capped Chickadee have a pattern of black, white, black on their faces which accentuates their beaks, potentially making them look bigger, stronger, and more threatening.

Posted on March 15, 2019 11:14 PM by zoey_november zoey_november | 5 observations | 0 comments | Leave a comment

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