Field Journal 6

Field Journal 6
04/19/2020

6:00 - 7:30am
04/19/2020
Spring Grove Cemetery, Florence, MA, 01062
28 degrees
Clouds: none

A white-throated sparrow woke me at 5:45am, and after briefly considering going back to sleep, I walked bleary-eyed into the dusky morning. A light frost coated the grass, and the sky was just starting to glow red in the east. Bird songs resonated from every tree as I made my way to the cemetery down the road. I saw a starling, chickadee, cardinal, chipping sparrow, and many robins on the short walk. The chipping sparrow seemed to be singing in response to another chipping sparrow further down the street. Perhaps they were singing to mark their neighboring territories.
The graveyard was an interesting habitat to observe birds. The few trees seemed to serve as prime singing platforms, while most birds pecked at the grass. Robins sang and squabbed in the trees, and some agonistic behavior was apparent between them. Often a bird would be driven out of a tree if the tree was already occupied, indicating that they were defending territories. Two robins were either fighting or copulating in short flights a few feet off the ground, and both actions demonstrate reproductive-related activities.
Lots of chipping sparrows were foraging in the grass, and some were singing on display in trees. A pair of song sparrows seemed to be checking each other out in one tree- one would hop away and the other would follow. Maybe it was a female testing a male’s interest, seeing how he responds to her movements? I moved to take a picture and scared one of them away.
I seated myself under a tree to make a sound map. There was a robin in literally every direction, both near and far. This makes me think that they were singing to attract females rather than defend a territory, because given their abundance, their territories would likely not have been large enough to be worth defending (also, there are not enough nesting sites in the graveyard to accommodate territories for all the singing birds that I saw). Also audible were two white-throated sparrows further away. In class, we talked about how white-throated sparrows have a lower-pitched song that carries well through dense vegetation, while the chipping sparrow has a high-pitched song that carries relatively well over open spaces. Indeed, the chipping sparrows were common in the open graveyard, while I only heard the white-throated sparrows from the far-off trees. A song sparrow was also singing nearby. A flicker was drumming and calling incessantly from a nearby tree. I presume that the drumming served communicative rather than foraging purposes, because it was accompanied by loud calls. There were three other flickers foraging in the grass- they did not seem to care whether the calling flicker was trying to drive them away or impress them. My map showed the birds to be spaced out as best they could be. It occurred to me that my map only accounts for male birds. In most birds, it falls on the male to defend a territory and attract a female through song, but I wonder about the female birds that do not show up on this map. Are females in some species territorial with each other? Singing to attract mates?
It is likely that the chipping sparrow I passed who was singing in my neighbor’s yard and the chipping sparrow singing from a tree in the graveyard had different qualities of habitat. Chipping sparrows feed mainly in grass, a resource found in greater abundance in the graveyard than the front yard, the latter being very shrubby. However, the mown lawn of a graveyard may not offer much food, given that it is a monoculture, while the yard may have a wider variety of plants and food sources. Also to consider is that sparrows like to build nests 3-10 feet from the ground in shrubs. The yard territory has far more low-lying shrubs than the graveyard in which to build nests. This may indicate that the chipping sparrow in the yard has a relatively better territory, and thus may have a fitness advantage over the sparrow in the graveyard.
I did not see any nest-building activities on my walk, likely because there are not good nesting materials or sites in the graveyard. Northern Flickers nest in tree cavities that they have either excavated or found/reused. Their cavities are not lined with anything but have a pile of woodchips at the bottom, meaning that Flickers do not need to forage for nest materials. The graveyard where I saw the Flickers did not strike me as a good nesting site, given that the trees are very exposed to weather, although the forest lining the edge of the graveyard may make a good nesting site.
White-throated sparrows build their nests on or very close to the ground. They line it with moss, grass, wood chips, twigs, and pine needles. Fine grasses, rootlets, and deer hair are also incorporated as in inner lining. These are all materials that would be found in the forest, so I imagine a white-throated sparrow would have a difficult time building a nest using materials sourced from the graveyard. There is also no cover at ground level, which would leave the nest in a vulnerable position.

Publicado el abril 20, 2020 08:20 TARDE por gmsaveson