|PRBO has been studying seabirds on the Farallones since 1968, compiling nearly 40 years of information on marine ecosystem change and the effects on seabird populations. The past two years of our study have revealed unprecedented reproductive failures, substantially lower-than-normal ocean productivity, and unusual large-scale ocean climate fluctuations. Low production has reverberated through the food web, resulting in noticeable and immediate effects on Farallon seabirds; many species have experienced poor reproductive success and high chick mortality. In 2006, Cassin's Auklets suffered near total reproductive failure for just the second time in nearly four decades; the first was 2005. Pelagic Cormorants, Pigeon Guillemots, Rhinoceros Auklets, and Common Murres also had very poor success this season. Compared with the remarkably productive years of 1999-2002 (which have resulted in large increases in the murre population, noted in the above article by Emily Tupper), conditions in the past two years suggest that the ecosystem may be changing in unpredictable ways, with a potential for long-term negative effects on seabird populations.--Pete Warzybok, PRBO Farallon Biologist, and Bill Sydeman, PhD, Director, PRBO Marine Ecology Division|
A few minutes later I reach for the door of a small shed-like structure, a bird blind that fits snuggly into the rocks of the ridge. Once inside, I plop into a folding metal chair and pull back the wooden hatch on the window.Suddenly I'm hit with the voices of 15,000 Common Murres: the sound surges past me on fresh salt air, flooding the blind. Now I'm awake! I scan the steep island slope below: birds are everywhere. They cling to the jagged rocks, they line the cliffs, they pack onto ledges. Dancing, flying, and coming and going, this colony flutters with life. Murres shuffle their eggs and stretch, they preen their tuxedo feathers and flap their wings, greet each other loudly with garbled voices, and excitedly examine their eggs.
The colony on Southeast Farallon Island has been growing in size for the past several years. Common Murres have responded to productive ocean conditions and abundant food supplies with high reproductive success and survival of young birds. With so many new recruits returning to the island, the colony continues to grow: it now numbers near 200,000 birds--a staggering increase from the 55,000 observed just six years ago.
|Emily Tupper spies on Common Murres from a blind on Southeast Farallon Island. Photo by Pete Warzybok/PRBO|
I flip open a battered binder to pages of breeding data. Glancing at my watch, I record the time and get to work. One of my many duties as an intern is to monitor the breeding success of a population of color-banded murres scattered across the hillside. Putting bands on these birds is like giving them names. It allows us to get to know them and follow the same individuals over many years. Every year they return to the same small area of the rocks to lay their eggs and rear their chicks. Their bands tell us who they are and give us an idea of their age. Murres are long- lived, and some that I am studying were banded 21 years ago! My job is to watch each of these known birds every day to see if they have an egg or a chick and to determine if and when that chick fledges. It's a daunting task that can take up to four hours every morning, but when a bird finally moves and I see its brand new chick, I gleefully record "bird over chick!" in the binder.
Lifting my binoculars, I focus on a large round and lumpy rock we call "Australia." Then, using it as a guide, I count two birds to the left and see the banded bird that is tucked up against a smaller stone. Yesterday his egg hatched. Full of anticipation, I wait for the bird to shift and show me his growing chick. But as he stands and peeks beneath his feet, my heart sinks. There between his banded legs is the limp body of a starved chick. Inches away I see the dried body of an anchovy, too large for the chick to swallow. Unfortunately, this has become a common occurrence this season, and many chicks have died within the first few days of hatching.
As I record this phenomenon, questions burn in my mind: why? Why aren't the adults finding small enough fish for their chicks to eat? Aren't the fish right there, just beyond that surf? It appears that the answer at present is no. Something has changed: the ocean is not as productive this year. There is less food available for young fish when they hatch, so there are few small fish for murres to feed their chicks. The adult murres are doing the best they can, flying out over the water in search of schooling salmon, anchovies, smelt and sardines, diligently returning to the colony with their catch and attempting to feed their chicks.
Thankfully, some will be successful. Some adults will manage to find the small fish that these chicks so desperately need. Brooded by their parents, the chicks will quickly convert fish into muscle and feathers. As they grow they will be able to eat larger and larger fish; then finally they will jump to the sea and learn to hunt for themselves. I look forward to that day.
Maybe next year will be better. Maybe more eggs will hatch and more chicks will feast and grow to fledging. Until then I'll enjoy my perch on the edge of the world --waiting, watching and hoping these young chicks will fly.