Research Technical Report

Mortality of Northern Fulmar (Fulmarus glacialis) in California During October 2003

Harvey, J.T., H.M. Nevins, S. Hatch, J. Adams, J. Hill, J. Ames, J. Parkin, K. Newton and T. Hass (March 2004)

Poster presentation at the Sanctuary Currents Symposium, Seaside, CA

ABSTRACT

During October 2003, an unusual mortality of Northern Fulmar (Fulmarus glacialis) occurred in central California. In Monterey Bay, we recorded high deposition of dead fulmars on beaches (mean = 12.8 ± 3.2 SE birds km-2, range = 0.3 - 25, n = 10 beaches), and observed high densities of live fulmars at sea (mean = 14.0 ± 4.7 SE birds km-2, range = 2.4 - 40.1). We conducted post-mortem examinations of 186 fulmars to determine age, colony of origin, and probable cause of death. Necropsies indicated 96% of birds examined were hatch year and 4% were after hatch year based on molt and bursa. The proportion of color morphs, 92% dark and 8% light, suggest birds originated from colonies in the Gulf of Alaska (GOA). Bill measurements were similar to those of the Semidi Islands, AK. Concurrent studies of satellite-tagged fulmars showed movement of fulmars from the Semidi Islands to central California. Fulmars were in poor body condition as evidenced by reduced body mass (male, mean = 453 ± 60 g, n = 32; female, mean = 383 ± 42 g, n = 41), atrophied muscles and livers, and no subcutaneous fat reserves. Stomachs were virtually empty, containing few squid beaks and plastic fragments. Starvation may be the main cause of death; young birds may have been disproportionately affected because they did not have energy reserves to buffer against food limitations. Persistent storms in the GOA may have contributed to this starvation event, either by preventing foraging or reducing prey availability during their southerly migration.