THE MOUNT SUTRO BIRD WATCHER: SONG SPARROW
- Maryann Rainey
- Oct 2
- 3 min read
Grab your binoculars!
Calling in a thin raspy chirp or singing a wild assortment of songs, always with a characteristic “lisp” mid-song, the Song Sparrow is the ubiquitous bird of Mount Sutro, a year-round resident. In my early years as a birder, I was baffled by the variety of calls that this bird would project from the underbrush, singing throughout the day. Now, with practice, I have come to recognize this bird of many songs.
The Song Sparrow, a medium-sized bird with streaked brown and tan plumage of the upper body, is distinguished by the brown spot in the center of a pale chest. The head has a brown crown stripe, a dark eyeline separating the light eyebrow from the cheek, and a thick malar stripe. Sexes are similar. The Song Sparrow, with a chunky sparrow-type bill designed to crack seeds, feeds on small seeds, some berries and small insects.
Visible characteristics, such as size and coloring, have long been used to identify subspecies of the Song Sparrow that are found throughout North America. The Summer 2025 edition of Living Bird, published by Cornell Lab, devotes an article, “Finding Extraordinary in the Ordinary”, to the study of diversity in the Song Sparrow in North America. The study of the diversity of the Song Sparrow began in 1981 by Peter Arcese. For years his observations recorded visible characteristics, such as size and plumage variations which led to the identification of 25 Song Sparrow subspecies, birds with physiological variations that could successfully breed. Analysis of the genomes of birds was added to the observations in 2016. The genomes of 316 individual birds, representing 25 distinct subspecies, were analyzed in the Cornell Lab’s Fuller Evolutionary Biology Laboratory in Ithica New York. A supercomputer owned by Cornell Lab was used to analyze many data points: the physical characteristics and DNA of the birds, as well as details of the habitat such as temperature range and moisture. Bird specimens that were collected in the same locations and meteorological records that were collected over the course of many years, allowed the researchers to see changes over time and to make correlations to weather changes, such as El Nino and La Nina.
The subspecies of Song Sparrow of the San Francisco Bay Area is about one third the size of the subspecies found in the Aleutian Islands. Probably, the larger body of the northern bird allows it to conserve heat in a cold environment. In the Pacific Northwest, the Song Sparrow has darker plumage, the additional melanin in the feathers possibly provides protection against microbes that thrive in moist environments. Desert-dwelling Song Sparrows of the Southwest have relatively pale plumage, thought to provide camouflage against the light browns of the desert, providing shelter from predatory hawks above.
The variation of characteristics within the Song Sparrow species probably accounts for the fact that Song Sparrows are found throughout North America, a large land with a variety of habitats. Some subspecies of Song Sparrow migrate long distances, some do not. There is evidence that migrating populations of subspecies of Song Sparrows have increased survivorship over subspecies that do not migrate. The mixing of genetic characteristics that come with migration appear to confer better survival, as adaptation to climate change benefits populations with greater genetic variation.
During your walk on Mount Sutro, listen. It is very likely that the Song Sparrow will be calling and singing trailside. Savor the moment.
Check out the link for more information, including identification, life history and sounds.
