by Yvonne Chan

Yvonne is a PRBO field biologist who served as an intern at Palomarin Field Station in 1996, after graduating from Pomona College in Claremont, California.

I arrive just as the sun rises above the horizon. Its rays transform a half-meter tall, homogeneous, flat plain into a landscape with hills and valleys of pickleweed, all connected by shining spider webs. Hearing a female Song Sparrow call behind me, I whip around hoping to see the trembling movement of pickleweed that betrays her nest location. This morning I only catch sight of her flitting through the air and diving down, becoming lost in the sea of green clumps. The challenge is to keep my eyes focused on that particular clump of pickleweed until she pops up to feed in a different clump. If I can track her appearances and disappearances for ten minutes while she forages, she will lead me back to her nest. Of course, this is easier said than done.

I am responsible for nest finding and monitoring at two San Pablo Bay sites in PRBO's tidal saltmarsh project - Petaluma Marsh and China Camp State Park. Ryan Burnett and Bill Kronland, fellow field biologists, are responsible for the Suisun Bay sites at Rush Ranch and Benicia State Park. Each marsh has its own personality. At Petaluma Marsh, with few channels and consisting almost solely of pickleweed, Song Sparrow territories are dispersed evenly over larger areas. At China Camp, carved by winding mazes of sloughs bordered by gumplant, their territories are densely packed in lines along the sloughs; each sparrow pair has its own "slough-front" real estate.

The high densities have enabled me to observe hundreds of nests and witness occurrences that I may not have otherwise seen. China Camp is where I discovered one of my most exciting nests. I found it newly built. Returning four days later I was shocked to see seven eggs inside. Since the normal clutch size of Song Sparrows in the marsh ranges from two to four eggs, and the female will lay one egg a day, this nest most likely contained eggs from two different females. I visited regularly to see if the eggs would hatch, and when I parted the foliage two weeks later, seven little heads popped up to beg; together their tiny bodies already filled the nest cup. Only six lived long enough for me to band, but all six then fledged a few days later.

In addition to unusual acts of Song Sparrows, I have witnessed commonplace but wonderful events. I watched a nestling pushing apart the two halves of its shell; it was hard to believe that such a fragile creature had so much strength. I later returned to discover that same nestling gone. Two-thirds of the nests in the marsh succumb to racoons, house cats, snakes, or other marsh predators. Yet even with these disappointments, many miracles take place in the marsh, and I feel privileged to glimpse what is hidden underneath the pickleweed of San Francisco Bay marshlands.



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