Diario de gmsaveson

Field Journal 3
3/12/20

Time: 9:00am
Date: 11 March 2020
Location: Fitzgerald Lake Conservation Area, Northampton, MA
Temperature: 36℉
Cloud cover: 5% cloud cover
Wond: No wind

I began my observations on a path through a forest of mixed conifers and deciduous trees. There were so many birds I was overwhelmed and did not attempt to count them all. Most noticeable were the Black-capped Chickadees, of which fifteen or so flitted between branches. Also present were at least two White-breasted Nuthatches, at least three Tufted Titmice, one Brown Creeper, two Downy Woodpeckers, and several (maybe five?) Dark-eyed Juncos. I took this opportunity to pshh, and succeeded in attracting two chickadees to nearby branches. I sat down and pshhed some more, but the Downy Woodpecker high above did not take notice. A titmouse briefly perched on a nearby branch to investigate me, turning so that it could focus an eye on me before flying off. While pshhing, I tried to make the air whistle through my teeth to better mimic the high-pitched cheeps of the Black-capped Chickadees. Because chickadees form the nucleus of mixed-species flocks, both chickadees and other small birds will be attracted to their sounds. The mixed-species flock I was observing gradually moved on; first the chickadees left, then some of the other birds, followed by the woodpeckers (they spent longer on one tree than the other birds) and titmice. Thinking back to the other mixed-species flocks I have observed, I notice that they do not linger in one place for extended periods. This could be due to my presence, but it also makes sense that these foraging birds need to constantly be finding fresh sites.

Next, I walked through the woods along the edge of a marsh thick with cattails. Song sparrows and Red-winged Blackbirds were ceaselessly singing. The sparrows were most common in low vegetation, hidden among the cattail stems and in the branches of small shrubs.The blackbirds perched themselves more conspicuously on taller dead trees. One male in particular was clearly trying to be as visible as possible, and puffed his brilliant red wings with each song. This behavior indicates that he was defending his territory and attracting mates, a typical spring activity.

I wonder why the sparrows were more seclusive than the blackbirds, and whether female blackbirds are also as bold as the males (I did not see any females). The different plumages of song sparrows, female blackbirds, and male blackbirds give insight to the different evolutionary purposes of their colors. Song sparrows and female Red-winged Blackbirds are both streaked in neutral browns that provide good camouflage, while male Red-winged Blackbirds have brilliant red and yellow shoulders that dramatically contrast their black bodies and surroundings. After turning to the internet, I learned that the loud, alarm-clock-like songs are sung by male RWBs but not females, and that their vocalizations, like their plumage, are meant to be as noticeable as possible. Considering that RWB males mate with multiple females that nest in his territory, it makes sense that males will be more successful if they are better able to attract mates and have a strong territorial presence, while females only need to choose mates and therefore see no evolutionary advantages from bold colors. In fact, the abundance of predators of RWBs and their nests will favor coloration in females that are as inconspicuous as possible. Song sparrows of both sexes are colored for camouflage. According to the literature, female song sparrows select mates based primarily on their songs, so perhaps the benefits of bright colors are not as critical to male reproductive fitness as the costs associated with increased visibility to predators.

I also wonder whether the songs were responding to one another, or simply independent calls meant to be heard but not responded to. The blackbird songs did not overlap much, as though the birds were coordinating their songs. Also interesting to note was that only the last note of the blackbird song was audible from far away- I only heard the softer intro notes from nearby birds. I also liked hearing the variation in the song sparrow’s song. Does each sparrow have its own song? How many different songs are in one sparrow’s repertoire? Also seen during my stop at the marsh was a red-tailed hawk and four cardinals.

Next, I walked along the lake and spotted many waterfowl. Two geese were dunking their heads into the shallow shoreline water (I assume they were feeding) about ten feet away. I could hear them making soft, low sounds, almost as though they were humming to themselves. Were they communicating with each other? Reassuring each other that the other was nearby? Or making noise for some other purpose? Further out on the lake were many more geese and ducks, including Common Mergansers, Mallards, and at least one Bufflehead. They used sound as an alarm, calling out in short, loud quacks after spotting me.

Although it is still early March, signs of spring were plentiful. A honeybee was pollinating a blooming crocus by the main road, skunk cabbage was emerging along the marsh edges, and a deer tick was crawling up my leg.