3/8/21 FJ3: Riverwalk to Salmon hole in Winooski

Time: 12:45p - 2pm
River Walk to Salmon hole near Gardener's Supply in Winooski VT.
Clear Sky, sunny, 25F 9mph winds
Habitat: winnooski river, mixed forest of mostly deciduous trees without much leaf cover, sparse coniferous trees, dense underbrush of mostly woody plants, a few patches of cattails, close proximity to the road at the start of the trail.

During this birding excursion I was surprised to see Ducks! I observed 4 Mallards just chilling in the river among the ice chunks and thought about how absolutely freezing the water must be. It was fairly warm in the sun, but that doesn't discount the frigid water the Mallards were swimming and feeding in. I did observe them feeding, as they dunked their heads and went bottoms up a few times. I'm sure there are a variety of fish in the Winooski river as well as aquatic plants and algae, although I can't speak on the availability of these during the winter. I would imagine more small fish, snails and crustaceans would be available in the summer months, therefore more cold weather greens or potentially even insects might be favored in the colder months. Evidently there was enough to go around for all 4 individuals (2 male 2 female) to hang around. I would imagine having waterproof outer feathers help keep the ducks from actually being wet and thus freezing, paired with thick downy both help insulate the ducks during these winter months. Perhaps Mallards also have some afterfeathers to provide additional insulation, although I believe afterfeathers are more common in larger, colder climate birds. But what about their feet? My hands absolutely froze solid on my bird walk, one would think their feet should just fall off of frostbite in the winter. After a bit of research, paired with lecture material, I learned that basically the down feathers that insulate their body cavities do such a good job keeping them warm that it created a counter current exchange function in their feet. The blood going from the body to the feet warms the blood leaving their feet, effectively keep them warm enough to not freeze off: the blood in the arteries is warm and in close proximity to the veins that the heat from the arteries also warms the veins. Assuming the other water bird I saw was a Common Merganser I would imagine the same principles apply to them, or any colder climate waterfowl. I believe they'd all share these traits due to homologous evolution (development of similar/same traits due to a common ancestor) and have been kept due to their obvious effectiveness at keeping these birds warm. I'd imagine sleeping close to the water or in the water would be beneficial to these water fowl types to protect them from predatory mammals. These birds were also seen not feeding, but basking in the sun along the shore, again I assume the water offers a lot of safety to these types of birds even throughout the day, allowing time to rest and conserve energy. The two male Mallards did seem to squabble a bit with each other, I don't think its mating season but I wouldn't be surprised if they were pairing up in preparation for it come early spring. This though was further proven by the 4 ducks splitting up in to male/female pairings and eventually splitting in pairs from the group.

The smaller passerine song birds I saw today also have down feathers to insulate their bodies, and I'd imagine have a similar counter current blood exchange to keep their legs warm, paired with specialized skin (from possibly their reptilian ancestors) to further help insulate their legs. The skin along their legs is almost scale like and may have evolved from reptilian scales to be more insulative and tough to endure perching on rougher surfaces such as tree bark. These birds, the Black-capped Chickadees and the Northern Cardinal were seen in coniferous pine (?) trees near dense undergrowth around a well dead tree. I'd imagine these birds feed primarily on seeds from these pine trees, and insects may be scavenged from snag trees, suggesting why these birds were hanging around in this area. However, not a lot of these smaller song bird types were seen, so I'd assume noon is probably not their ideal feeding time, but rather their time to stay warm, maybe digest their breakfast (also generates heat), and overall conserve energy. In the summer these birds may feed on a wider variety of seeds and bugs as they both become more abundant in the warmer months. There were a lot less pine trees the further down the trail I went, and also less of these song birds, they seemed to really concentrate in the pine/coniferous trees, I believe because they over the most cover, especially as a lot of the trees were bare. I did notice some evidence of woodpeckers (see pics attached to Hairy Woodpecker observation) but no actual woodpeckers. Again, this is probably because they don't feed in the middle of the day but probably closer to dusk when it's slightly darker out. This also makes sense as the time I did see a Hairy Woodpecker (2/28) was around 3-4pm, much later in the day (not at the river walk location though, see observation location). Feeding at dust makes these smaller prey species of birds less visible due to the changing in lighting, so it might be an advantage to them to hid from raptors and such to feed in times of lower light.

Lastly, the soaring birds: Herring Gulls and American Crows (larger black birds could've also been some kind of Raven) were also observed on my walk. Neither of these bird species were seen on the ground but rather circling the same areas above the Winooski river (at separate instances and not together). Again down feathers and specialized blood flow help these birds, but I also think they use warm air streams to warm up as well. Judging by the amount of time both species spent above the river I'm confident their must have been a warm up draft in the area that they appreciated. I didn't see these birds eating but I know both can be scavengers and like living around human civilizations eating scraps and such to supplement their wild type diets. The gulls hung around the most, 12 or more individuals enjoying sun as well as the updrafts off the river. I'd assume they must spend mid day conserving energy and finding warmth and feeding during the dusk hours similarly to the songbird's patterns of eating.

Julkaistu maaliskuu 7, 2021 11:57 IP. käyttäjältä jamiek347