The marbled murrelet is a small seabird that lives along the Pacific coast of North America. This elusive bird spends most of its life offshore, diving for fish and invertebrates. However, it comes ashore to nest, laying its single egg high up in the branches of old-growth coastal forests. The marbled murrelet has declined significantly due to loss of its nesting habitat and is listed as threatened under the Endangered Species Act. Understanding its migratory patterns is an important part of marbled murrelet conservation efforts.
Quick Answers
Yes, the marbled murrelet does migrate. Its migratory patterns vary across its range, but generally marbled murrelets undergo relatively short migrations between breeding and wintering areas. In northern parts of their range (Alaska and British Columbia), marbled murrelets migrate south to overwinter in more temperate coastal waters. Farther south (Washington, Oregon, and California), some marbled murrelet populations are resident year-round in breeding areas, while others undertake short-distance migrations. Migratory movements appear to be influenced by food availability and weather conditions.
Marbled Murrelet Breeding Range
The marbled murrelet has a breeding range that extends along coastal forests from the Aleutian Islands in Alaska to central California:
- Alaska – Aleutian Islands, Gulf of Alaska, southeast Alaska
- British Columbia – coastal forests
- Washington – primarily western Washington from the Strait of Juan de Fuca north
- Oregon – coastal forests west of the Cascades
- California – coastal redwood forests south to Monterey Bay
Within this range, the marbled murrelet nests in mature and old-growth forests up to 80 km inland along river valleys and in mountainous areas. It requires large, moss-covered branches for nesting.
Marbled Murrelet Winter Range
In the winter, marbled murrelets are found primarily in nearshore marine habitats within their overall breeding range, but extending farther south to:
- Oregon
- California – south to San Diego
- Baja California, Mexico
They generally occupy sheltered bays, inlets and other protected coastal waters. During winter, however, they can also be found offshore in subarctic and temperate waters up to 200 km from land.
Migration Patterns
Alaska and Northern British Columbia
In Alaska and northern British Columbia, marbled murrelets are considered migratory, moving south out of the northern breeding areas in winter.
- Birds nesting in Prince William Sound, Kenai Fjords and other Gulf of Alaska sites migrate as far south as Oregon and even central California.
- Birds from Haida Gwaii and other northern BC sites move south primarily to Washington and Oregon.
- Migration begins in September/October and runs through December.
- Return migration to breeding areas begins in March.
- Migrating flocks fly considerable distances offshore and along coastlines to reach wintering grounds.
Washington, Oregon and California
Migration patterns are more complex and variable south of British Columbia. Some key aspects:
- In Washington, populations are partially migratory – some birds migrate short distances while others stay resident year-round.
- Oregon hosts both resident and migrant populations from British Columbia, Washington and Alaska.
- Central California coast populations are mostly resident.
- Farther south in California, an increasing portion of the population are winter migrants.
Research indicates marbled murrelets show strong nest site fidelity. The same individuals tend to return to breed at the same inland nesting areas year after year. However, they may move to different wintering areas along the coast.
Factors Influencing Migration
Marbled murrelets appear to base their migratory movements on food availability and weather conditions:
- They leave northern areas when prey becomes less accessible due to ice buildup.
- They move south to find more abundant food supplies in winter.
- They are more likely to migrate in years with unusually cold weather or storms.
- Younger birds may disperse farther than adults.
Radio telemetry studies found marbled murrelets adjust migration on daily, seasonal and annual scales depending on conditions. Their winter movements are quite dynamic.
Threats During Migration
Marbled murrelets face a variety of threats during migration:
- Oil spills – Migrating birds are vulnerable to oil spills at sea. Spills near migration routes or wintering areas could impact a large number of birds from multiple populations.
- Gill-net fisheries – Murrelets drowned after being caught in gill nets used to catch salmon along migration routes.
- Predation – Peregrine falcons and other predators prey on murrelets during migration.
- Habitat loss – Loss of nesting habitat and degradation of wintering habitat negatively impacts migratory populations.
Protecting migration corridors and network of connected marine and terrestrial habitats is an important part of marbled murrelet conservation.
Importance of Understanding Migration
Determining the migration patterns and migratory connectivity of marbled murrelet populations has important management implications:
- Identifies key marine habitat areas used during non-breeding season.
- Helps determine how distinct inland breeding populations are from each other.
- Allows population modeling to determine how impacts in one area (like an oil spill) will affect other areas.
- Informs population monitoring and distribution of conservation efforts across the range.
Advanced tracking technologies and genetic studies are improving knowledge of murrelet migration and year-round habitat use. However, there are still significant knowledge gaps.
Conclusion
The marbled murrelet undertakes relatively short-distance migrations across its coastal Pacific range. Migration patterns vary, with northern populations migrating south to overwinter while some southern populations are resident year-round. Food availability, weather, nest-site fidelity, and natal dispersal influence migratory movements. Protecting inland nesting habitat and interconnected marine habitats along the coast is crucial for conserving migratory marbled murrelet populations. Further research can provide critical information on migration behavior, connectivity and conservation priorities. Understanding migration is key part of recovery efforts for this threatened seabird.
Location | Migration Pattern |
---|---|
Alaska and northern British Columbia | Longer distance migration south to Oregon/California in winter |
Washington | Partial migration – some resident birds, some short-distance migrants |
Oregon | Mixture of resident birds and migrants from north |
California | Central coast more resident, increasing migrants farther south |
Migration Timing | Life Cycle Events |
---|---|
September – December | Fall migration to wintering areas |
March – April | Spring migration back to breeding areas |
May – August | Breeding season – courtship, egg-laying, incubation |
September – February | Overwintering in coastal marine habitats |
References
- Mckibben, S. M., Peterson, W., Woodbridge, B., Marcot, B. G., Pollock, K. H., & Kittel, G. (2017). Marbled murrelet effectiveness monitoring, Northwest Forest Plan: 2016 summary report. Gen. Tech. Rep. PNW-GTR-967. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 21 p., 967.
- Peery, M. Z., Beissinger, S. R., Newman, S. H., Burkett, E. B., & Williams, T. D. (2004). Applying the declining population paradigm: diagnosing causes of poor reproduction in the marbled murrelet. Conservation Biology, 18(4), 1088-1098.
- Piatt, J. F., Kuletz, K. J., Burger, A. E., Hatch, S. A., Friesen, V. L., Birt, T. P., … & Irons, D. B. (2007). Status review of the marbled murrelet (Brachyramphus marmoratus) in Alaska and British Columbia. US Geological Survey Open-File Report, 2006-1387.