September 13, 2000 Feature:

By Elizabeth Derryberry '00

In the predawn, we fumbled inside the one-room trailer, grabbing bagels and mugs of coffee and stuffing Power Bars into our pockets in anticipation of the long day ahead. We were putting off the plunge into the freezing outside air, pressing together in that cramped trailer for a last touch of human warmth. The sun was rising, though, and we had to leave each other's company if the day was to be successful.

The step down from the trailer bent under the heavy boots seeking it blindly in the half-light, and we stumbled into the crisp mountain air. Earlier, we had run from our warm sleeping bags to the warm trailer, and now we ran for the heat of the trucks that would carry us up the steep mountain road into Tioga Pass. The field site for the study of mountain white-crowned sparrows was at 10,000 feet, on the edge of Yosemite National Park, and we, the Princeton research team, traveled there every morning as the first golden light picked out the tips of the higher peaks.

It was near the end of my six-week-long senior research trip, and I had been unable to find a few of the sparrow nests along Lee Vining Creek (LVC). I needed as complete a data set as possible for my study of avian malaria, which required that I identify every pair of sparrows, find their nests, and bleed both the parents and the nestlings. Today, I decided not to run a trap line and catch adults; instead, I would concentrate on my search for those few remaining nests that I needed.

One of the graduate students, Beth, dropped me at the bottom of LVC and continued on in her dilapidated blue truck to a field site farther up the pass. Suddenly alone, I walked along the creek carrying less than I usually did. I had only my medical kit with its needles, capillary tubes, cotton, ruler, weight bag, bands, and banding pliers. I used these tools to identify and collect the blood of the sparrows that I found within the field site. The needles and tubes were tiny, a scaled-down version of the implements used to collect human blood. The bands, colored bracelets for a bird's legs, were used to mark the birds so that they could be identified at a distance and over many years of data collection.

Besides the tools I carried, my NorthFace pack held gorp - that tasty combination of peanuts, raisins and M&Ms that one loves in the field but which loses all appeal by the end of the season - and a full water bottle. On the back of the NorthFace, I also strapped an old potter's trap just in case I needed to catch a bird.

This morning I was looking for "Navy Girl." She was a small female that I had banded in blue and white a few weeks ago. Because I had spent a lot of time tracking her, and her bands reminded me of a sailor, she gained a name, as some of the birds do. In their usual wasteful manner, weasels had ransacked Navy Girl's first nest, killing her tiny babies and leaving them scattered on the ground. I had noticed her collecting food a few days before, though, and hoped she might have a second nest. Settling down near where I had seen her last, I passed the time watching the dawn shrink the shadow cast by the mountain behind me, eagerly anticipating the light's progression as it marched toward my toes. I had never followed the movement of the sun until this summer. Now it was each morning's constant focus, as I endured the unique, painful numbness of frozen toes in stiff hiking boots until, at last, the sun crept its way up my boots and wound its warm fingers down around my ankles.

Time passed, and Navy Girl did not show. I began to wander across the meadow, hoping to stumble upon her nest. The ground lay flat for 10 to 20 meters on either side of the creek and then rose abruptly to form the mountains in whose shadow I stood. The valley's sharp narrowness made it a dramatic setting, like the set of an old Western movie. At any moment I expected a posse of cowboys to round the corner, disrupting my solitude. Their yelps would have echoed with the calls of the pikas, those bunny-like creatures with piercing screams. The horses they rode would have impressed deep crescents into the thawing mud and brushed unawares through the wiry bushes supporting the fragile nests. The image lost its romance when I realized they could easily crush the eggs that took a mother so long to lay and me so long to find.

I had sometimes spent eight hours looking for a single nest, and I hoped this wasn't one of those days. I hunkered down in a bush, making calling noises. The cowboys would have laughed to see me. In a rare moment of luck, though, I came toe to beak with Navy Girl. She was carrying food, and before she could call out to shush her babies, I heard them faintly peeping to my right.

Gently but quickly lifting branches, I began to poke through the low willows. I wanted to find the nest before I scared the babies into leaving it too early. At a certain time, baby sparrows are supposed to fledge from their nest, but are still dependent on their parents for food. If a predator scares them, they will fledge early in an attempt to escape. This early fledge is dangerous for the baby and disturbing for a field biologist, because as the baby leaps from the nest it screams piercingly to let its parents know of its escape. This cry travels a long distance, and if any tourists are around, you get very funny looks.

At last I caught sight of the babies' soft bodies, in a nest that could barely hold them, their big eyes looking up at me. They looked like adults with their feathers and open eyes. I had found them just in time, and quickly I placed my hand over them to keep them from jumping. They squirmed, attempting to push through my fingers, and made frantic calling noises to their mother. Nervously watching my every move, Navy Girl boldly perched barely a foot from my elbow. I preferred to find a nest when there were only eggs, or at least chicks who were too young to cry out and worry their parents. Before they grow feathers, their abdomens are swollen, and their skin is so tissue-thin that their red heart, green intestines, and yellow stomach show through. They look like colored hard candies. Weasels love them.

I scooped the babies out of their nest and held them in my wool hat to keep them still. They soon slept despite the frantic calling of their mother and their father, who had just arrived. I sat down cross-legged and began the routine that was by now second nature. I held each baby in my hand with its neck between my two first fingers and its back pressed firmly against my palm. This tight hold was to prevent them from struggling and possibly hurting themselves. They had a certain feathery, dusty good smell and their soft down tickled. I secured a silver band on one of the chick's legs but did not color band it. They would only receive color bands once they returned to this site next year.

I proceeded to take a few drops of blood from under the baby's wing. It lay perfectly still and sleepily blinked its eyes. Because the day was warmer, the baby's blood flowed into its extremities, making it easier to draw a sample for DNA testing. Sometimes, when I had to bleed very early in the morning, when there was still frost on the ground, it was nearly impossible to draw blood, as the veins had retreated deep into the muscle.

After I had finished the same procedure on each of the four nestlings, I tucked the babies back into their nest. Fearful that they would attempt to fledge after being handled for so long, I repeated my tactic of covering them with my hand. As I held them still, gently pressing them into their nest, they eventually began to snooze again. Their little bodies rose and fell in a mound of gray fluff with awkward yellow legs sticking out haphazardly. I walked away quietly and left the parents in peace.

As the heat of the afternoon increased, I ambled along the creek, stripping off layers of now-burdensome clothing. It was near the end of the summer, and I was sensitive, like any other creature along LVC, to the slightest sound or movement. I had become so used to listening for the unique "seeping" call of a female sparrow as she flies over her nest that I would hear it in my dreams as if it were a foreign language and I were in an immersion program. As I walked, I heard a group of hikers, long before they saw me. Without thinking, I dropped into cover under a thick willow, hiding like the rest of the wildlife, still and watching. The hikers passed so close that I could hear them clearly, and they continued their conversation unaware of my eavesdropping.

I found nothing else that day, but I was triumphant about Navy Girl's nest. Those nestlings would be fledglings by tomorrow, and if I had waited, I would never have caught them as they darted about in the undergrowth.

Eventually, Beth picked me up where she had dropped me off earlier. It was much warmer than it had been that morning, and she perched on the ripped seat of her truck with "Dancing Queen" by ABBA cranked up on the radio. It was a shock and a relief to go from the silence of the mountains to raging disco on a highway now crowded with RVs and station wagons lined up to enter the park. Everywhere tourists hung out of their windows, their cameras busily capturing the grand vista of the Sierra Nevada. After winding down the narrow road, the brakes protesting at every turn, we finally made it back to the campsite, worn and desperately hungry.

In the evening, we came back together as a group. I curled up next to Beth, Regan, and Rodd on the 1970s-era orange and brown couch that matched the décor of our trailer. Cradling the nest book in my lap, I entered the data I had collected for the day: my Navy Girl nest and four new data points of babies. I joined my new blood samples with Rodd's and Beth's to spin them down in the centrifuge, which separated the different elements of the blood to be used for various tests. While we chatted about the day, I handled the blood, Beth made chicken fajitas, and Andrea mixed the salad with her famous miso-carrot dressing. It was always difficult to wait for that food, starving but happy in the company.

During dinner we all told funny stories about the birds and the hikers we had encountered. Conversation was a strange mix, part bawdy and part scientific. After dinner, someone would pull out a book, another a pack of cards, and always the bottle of whiskey would make an appearance. As the light faded, lines between postdocs, grads, professors, and even undergraduates would blur.

Outside the air was already cold again, and it was so hard to walk that short distance to the outhouse and then to the tent. The stars were still not out most nights when we went to bed. The last clear light cast into deep shadow the lateral moraines that embraced our camp and caught the rough planes of the huge boulders, also remnants of the glaciers, scattered around the site.

Only the soft calls of the grosbeaks and the crossbills interrupted the quiet of the night. They were my adviser's birds, and he kept them captive in the trailer to use as decoys during the day. The crossbills always follow a certain routine when they go to bed. That night, they made their call to roost as they would in the wild. They called each other to bed, admonishing those that continued to fly. Then they made soft peeping noises that were like a lullaby, and then, finally, they shuffled about, jostling for a good place to sleep.

Their pattern was much like ours. First we laughed and chatted, rediscovering each other's company after a long, solitary day. Then we exchanged good-nights and quiet jokes as we brushed our teeth and packed up for the next morning. Finally, we shuffled into our tents, wiggled into our sleeping bags, pulled a wool hat down over our ears, and made sure our alarm was again set for 5 a.m.

This essay was a winner of the Gregory T. Pope '80 Prize in Science Writing, awarded annually by Princeton's Council on Science and Technology in memory of Pope, a science writer who died of an aneurysm in May 1996. Derryberry conducted the research described in this essay in 1999 in Tioga Pass, California, for her Ecology and Evolutionary Biology senior thesis, under the guidance of Dr. Tom Hahn.

Derryberry will spend next year as a research intern with Save the Elephants, working on an independent project in Samburu, Kenya, with partial funding from Princeton-in-Africa. In the fall of 2001 she will attend Duke University as a graduate student in zoology, funded by a National Science Foundation graduate fellowship.

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