Skip to Main Content
Chapter 34: Offshore Occurrence Patterns of Marbled Murrelets in Central CaliforniaAuthor(s): David G. Ainley; Sarah G. Allen; Larry B. Spear
Source: In: Ralph, C. John; Hunt, George L., Jr.; Raphael, Martin G.; Piatt, John F., Technical Editors. 1995. Ecology and conservation of the Marbled Murrelet. Gen. Tech. Rep. PSW-GTR-152. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 361-370
Publication Series: General Technical Report (GTR)
Station: Pacific Southwest Research Station
PDF: View PDF (626 KB)
DescriptionWe assessed the occurrence patterns of Marbled Murrelets (Brachyramphus marmoratus) offshore of Waddell Creek, in central California. Data were derived primarily from cruises during the height of the murrelet breeding season, in June, between 1986 and 1994, as well as some cruises during the prebreeding period, February to early April. The large majority of sightings occurred within 10 km of Point Año Nuevo, directly offshore the species’ breeding area. Only three sightings occurred farther offshore (12-24 km). The physical factors that explained a small but significant portion of variability in murrelet occurrence were: (1) inverse relationships related to distance to breeding area (including ocean depth); and (2) relationships to recently upwelled water. Murrelets were least abundant during periods of El Niño-Southern Oscillation. An analysis of the availability of potential prey species indicated that murrelets were most abundant when more euphausiids were found from the coast to well offshore. Murrelets were absent in years when a large prey concentration occurred only close to shore, indicating that the birds were too close to shore for us to census. We suggest that the critical habitat of this population should include the nearshore marine waters within 10 km of Año Nuevo Island.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationAinley, David G.; Allen, Sarah G.; Spear, Larry B. 1995. Chapter 34: Offshore Occurrence Patterns of Marbled Murrelets in Central California. In: Ralph, C. John; Hunt, George L., Jr.; Raphael, Martin G.; Piatt, John F., Technical Editors. 1995. Ecology and conservation of the Marbled Murrelet. Gen. Tech. Rep. PSW-GTR-152. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 361-370
- Chapter 33: Offshore Population Estimates of Marbled Murrelets in California
- Chapter 37: Population Trends of the Marbled Murrelet Projected From Demographic Analyses
- Chapter 3: Comparative Reproductive Ecology of the Auks (Family Alcidae) with Emphasis on the Marbled Murrelet
XML: View XML