Marbled Murrelet (Brachyramphus Marmoratus) Population Trends and the California Current (FS-24-07)
The marbled murrelet (Brachyramphus marmoratus) is a federally-protected seabird species that occurs in the Pacific Northwest of North America (Figure 1). This bird nests on large branches of mature trees near the coast from Northern California to Alaska. Their population along the Washington, Oregon, and California coast appears to be greatly reduced compared to a century ago (Loehle et al. 2022), though exact figures are not available for historical levels. From the same study, the most common explanation for the decline is that harvest of mature trees has reduced their nesting habitat. For this reason, protection of mature forest in their nesting range has been a priority of the Northwest Forest Plan. Recent evidence, however, points to a decline in forage fish stocks as a potential population driver (Rivers et al. 2022). Although surveys of the coastal at-sea population have been ongoing as part of conservation efforts (McIver et al. 2022), there is uncertainty about status and trends of murrelet populations. Population trends often indicate how broadly conservation measures need to be applied to ensure long-term survival of a species. However, cause(s) of low population numbers for marbled murrelet, whether terrestrial or at-sea conditions, or a combination of these factors, affects what type of conservation measures are needed. To better understand this, NCASI (Loehle and Verschuyl 2024) recently investigated trends in murrelet populations and possible causes for any observed trends.
Keywords: marbled murrelet (Brachyramphus marmoratus); conservation; forest management
Authored by: Craig Loehle, PhD, Principal Scientist, and Jake Verschuyl, PhD, Director Western Forest Sustainability
Related Resources
Marbled Murrelet (Brachyramphus Marmoratus) Population Trends and the California Current (WP-24-04)
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