Grantee Research Project Results
Ecology and Conservation of the Marbled Murrelet (Brachyramphus marmoratus) in Central CaliforniaEPA Grant Number: U915973
Title: Ecology and Conservation of the Marbled Murrelet (Brachyramphus marmoratus) in Central California
Investigators: Peery, Marcus Z.
Institution: University of California - Berkeley
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 2001 through January 1, 2004
Project Amount: $80,316
RFA: STAR Graduate Fellowships (2001)
Research Category: Fellowship - Terrestrial Ecology and Ecosystems , Academic Fellowships , Ecological Indicators/Assessment/Restoration
The objective of this research project is to develop a novel approach, which I term the multiple competing hypotheses approach (MCHA), to determine which of three factors are having the greatest negative impact on marbled murrelet reproductive success and population viability.
The marbled murrelet (Brachyramphus marmoratus) is a highly endangered seabird, and previous research indicates that reproductive success is very low in central California. The murrelet has a unique life history; it spends most of its time foraging in coastal waters, but nests in old-growth redwood forests. The population of marbled murrelets in central California is threatened by a variety of environmental stressors including reductions in prey availability, declines in nesting habitat, and increased nest predation. Zooplankton populations in the California Current have declined by as much as 90 percent, more than 90 percent of old-growth redwood forests have been harvested, and populations of nest predators such as common ravens (Corvus corax) have exploded. However, as with many endangered species, which environmental factor(s) most threatens population viability is uncertain.Approach:
Applying the MCHA will involve developing a suite of competing predictions relating to murrelet demographic, behavioral, and physiological attributes. For example, if a lack of suitable nesting habitat, but not nest predation, limits marbled murrelet reproductive success, the proportion of breeders should be low and nest success should be high. I will design a series field tests for these predictions using a combination of radiotelemetry and physiological analyses.
I will estimate the rate of population change for marbled murrelets in central California using three different techniques: (1) a stage-based matrix model (parameterized with survival and reproductive rates); (2) counts of individuals at sea; and (3) a newly developed mark-recapture model (based on banding data). The three approaches treat in situ and ex situ recruitment differently, and by comparing resultant estimates of population change, I will determine whether marbled murrelets in central California represent a sink population that is being sustained by larger source populations to the north.Supplemental Keywords:
fellowship, marbled murrelet, Brachyramphus marmoratus, multiple competing hypothesis approach, MCHA, common ravens, Corvus corax, California, CA.