September 13, 2000
By Elizabeth Derryberry
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.
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
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
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.
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.
On the web:
Council of Science and
EEB Department: www.eeb.princeton.edu