Student Journal: summer dispatches from the field Offshore California: last stand of the endangered marbled murrelet
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marbled murrelet

About the project
Editor's note: Grad student Zach Peery will be filing regular dispatches from the field this summer. We'll publish his reports online here. This is Zach's first report.

AÑO NUEVO, CALIFORNIA - The Marbled Murrelet is a highly endangered seabird in California, so much so that is listed as an Endangered Species by the California Department of Fish and Game and as a Threatened Species by the U.S. Fish Wildlife Service.

This bird is unique within its family (Alcidae) in that it nests solitarily on the large, moss-covered limbs of large trees in old-growth redwood forests. Most other alcids nest in groups, colonially or semi-colonially, on coastal cliffs or rocky offshore islands. A variety of environmental factors threaten the murrelet or have contributed to historic declines in California. They include the harvesting of old-growth nesting habitat, oil spills, gill-netting, nest predation, anthropogenic disturbance at nest sites, and warming trends and contaminants in the marine environment.

Under the supervision of Dr. Steven Beissinger of the Dept. of Environmental Science, Policy and Management, I am studying the southernmost Marbled Murrelet population. They nest in the coastal redwood forests of the Santa Cruz Mountains and spend most of their time at sea in the near-shore areas, diving and pursuing small fish such as sandlance, northern anchovies, and sardines.

Previous research conducted by Beissinger and his former graduate student Ben Becker indicates that only about 500 murrelets remain in central California. The next closest population is located off of the Humboldt County coast in northern California and is part of the controversy surrounding the recently acquired Headwaters Grove. Apparently populations historically located off of Marin and Sonoma County coasts have been almost completely extirpated. Because of its isolation, our study population may be genetically distinct from other murrelet populations and constitute an "Evolutionary Significant Unit". If so, conserving this population will be critical for maintaining the genetic diversity of this species as well as its future evolutionary potential.

The Marbled Murrelet is an extremely secretive bird. It generally attends its nest site before sunrise and after sunset, does not vocalize near its nest, and nests approximately 200 feet up in the tallest trees in the world. This secrecy makes the murrelet nests exceptionally challenging to find. In fact, the murrelet was the last bird for which a nest was a located. At one point, the Audubon Society actually offered a bounty to the first birder who could locate a murrelet nest. It was not until 1974 that a nest was found in Big Basin State Park in the Santa Cruz Mountains. The bird's secretive behavior also makes it an extremely challenging study organism from a dissertation perspective. Nevertheless due to recent methodological advances in captures, radio-telemetry, and genetic techniques, we are beginning to gain insight into the life history of murrelets that previously would not have been attainable.

The overarching goals of my dissertation research is to: (1) determine if the Marbled Murrelet population in central California is declining; (2) determine which environmental factors are responsible for the declines; and (3) and develop management recommendations that will help recover murrelets in California.

The study can be divided into four different components that reflect different aspects of murrelet ecology and involve different field techniques. They include:

Movements Patterns: I am using radio-telemetry to investigate both the breeding season and migratory movement patterns of murrelets in central California. Increasing our understanding of what at-sea areas murrelets use is important for estimating and minimizing the impacts of oil spills.

Breeding Ecology: I am radio-marking individual murrelets and tracking them back to their nest sites. In doing so, I am able to determine which murrelets are nesting, where they are nesting, how many nests fail, and why nests fail. Because of their secretive life history, radio-telemetry is the only effective way to locate significant numbers of nests.

Demographic Assessment: I am conducting at-sea surveys from Half-Moon Bay to Santa Cruz to estimate changes in the number of murrelets from year to year. I am also catching and banding individual murrelets to estimate mortality and recruitment/birth rates. This will help us understand why murrelets in Central California may be declining, and whether we have a viable population.

Genetic Analyses: In collaboration with Dr. Vicki Friesen and Dr. Timothy Birt at Queen's University, I am collecting blood samples from the birds we are catching in order to conduct genetic analysis of murrelets in California. Genetic markers can be used to estimate rates of movement of individuals among breeding populations and will enable us to determine if larger murrelet populations to the north are augmenting the murrelet population to the south.

—Zach Peery


UC Berkeley
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