August 2008

The Hill is Alive with the Sound of Bird Song

By Mary Purpura and Silvano Purpura-Pontoniere

Potrero Hill’s soundscape leaves no doubt that ours is an urban neighborhood.  Cars speed along highways 101 and 280; airplanes fly overhead to or from the Oakland or San Francisco airports; and any manner of sounds from a myriad of industrial activities can be heard, particularly on the Hill’s eastern slope.  But in addition to these noises there’s another sound:  birds singing.

We live on the Hill’s southern slope.  While we can check the traffic flow on 101 from our front porch, we’re also greeted each morning with a concert of birdsong.  We took a few morning and dusk walks last month to get a better idea of who was doing all that singing.

On our first morning walk we immediately heard a wall of bird sound, cut through with a harsh “Squawk! Squawk!”  We didn’t need binoculars to spot the vocalists:  a flash of blue feathers and dark mohawk haircuts identified two Steller’s jays calling back and forth, one in a large pine tree, the other in a neighbor’s plum tree.  As we continued walking north on De Haro Street we heard the familiar “who-who-who-who”, with the first “who” pitched much higher than the final three, which were all on the same note.  It was the unmistakable call of the mourning dove, and as we looked around, with and without binoculars, we saw them all over:  on the ground, in trees, and on telephone wires.  Mourning doves are a little smaller than pigeons, brown, with a darker tail and wings, and dark spots on their wings.

Walking through Starr King Open Space, we saw a bird of prey in the high branches of a tree on top of the hill. The bird screamed before it soared away, and its broad, rounded wings and red tail told us that it was a red-tailed hawk.  As we descended from Starr King, little chirps and cheeps alerted us to a small brown bird, flitting quickly from branch to branch. We think it was a house sparrow, but they move so fast, they’re always a bit challenging to identify.

Further north and east on 22nd Street we saw the first of several Anna’s hummingbirds; some were sufficiently close to hear the whirr of their wings.  In the past, we’ve heard them call with a “tsk” sound, but on our recent walks they were mum.  They have bright green feathered bodies; the males have bright pinkish-red heads.

Despite the diversity of birds living in our community, the tireless mockingbird is responsible for much of the bird song we hear. Their songs are clear, loud, and long, and they’re famous for imitating other birds’ songs, as well as all sorts of other ambient sounds, from squeaking gates to barking dogs to human whistling.  We heard one a couple of years ago that went “ribbit-ribbit”.  We were thrilled to hear a frog in the neighborhood, but closer investigation revealed a mockingbird in the tree across the street whose opened beak, seen through binoculars, corresponded exactly with the “frog” sounds we were hearing.

Typically, a mockingbird – a bit smaller than a pigeon, with medium-gray wings featuring two distinctive white bars, and lighter gray on their undersides – will repeat a sound or phrase at least three times before switching to another.  If you whistle a repetitive song at a mockingbird for a sufficiently long time they’ll often echo it back to you.    

Mary and her 16-year-old son Silvano have lived on Potrero Hill for 13 years.  Let us know other urban ecology topics you’d like covered, or bird songs you’ve heard:  editor@potreroview.net.

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