In 2004 and 2005, we used satellite telemetry to (1) determine individual, regional residence durations during the annual molting period, (2) collect fine-scale movement information, and (3) measure the route and timing of re-migration to southern hemisphere feeding areas and breeding colonies (Fig. 3). Our team is motivated to understand the physical oceanographic characteristics that determine critical at-sea habitats (and habitats for important forage species like krill, juvenile rockfishes, and anchovy), and how shearwater movements may be influenced by upwelling events, variability in wind speed and direction, and diurnal and lunar cycles.

Currently, in 2006 with support from the Monterey Bay National Marine Sanctuary’s Integrated Monitoring Network (SIMoN), we will track the movements and habitats of 12 shearwaters captured in the Monterey Bay National Marine Sanctuary (MBNMS). We seek to further document important “habitat hotspots” within and beyond the MBNMS. A third season of telemetry also will allow us insight to interannual variability in ecosystem conditions affecting the coastal-shelf portion of the CCS. By coupling our investigations with physical oceanography and satellite remote sensing, we hope to use shearwater movements as a tool to understand how mobile marine predators function within dynamic ocean habitats.

Our results indicate that Monterey Bay and southern-central California are important destinations for these exceptional trans-pacific migratory seabirds. During May through September, shearwaters that have migrated here from breeding colonies in New Zealand and Chile spend considerable time (>2 months) in these waters feeding on abundant and perhaps, predictable concentrations of prey species to rebuild energy reserves, undergo energetically expensive molt, and store lipids prior to re-migration back across the Pacific.

Previously, hypothetical migration routes were based on extensive observations of birds from ships during surveys in the eastern tropical Pacific (Spear & Ainley 1999). Tracking individual birds, however, provides unique data to examine these hypotheses and allows us to examine detailed movements in association with satellite derived oceanographic and atmospheric conditions.

	Figure 3 Satellite tracking allows us insight into how sooties make their way back to the southern hemisphere. Individuals can travel 800 km per day and averaging about 25 km per hr, they can make it to New Zealand from California in about 17 days. In this example the daily locations are plotted over a mapped surface of Pacific Ocean winds. On 30 September, this individual was riding the front above a strong band of westerlies, perhaps en route for a colony in Chile. Colored vectors show wind direction and magnitude in m/s (scale at lower right; map courtesy of seaturtle.org)

Literature Cited

Briggs, K. T., and E. W. Chu. 1986. Sooty Shearwaters off California : distribution, abundance, and habitat use. Condor 88:355–364.

Spear, L. B., and Ainley, D. G. 1999. Migration routes of Sooty Shearwaters in the Pacific Ocean. Condor 101:205–218.

Project Partners

This ongoing study is a collaborative effort among scientists from Moss Landing Marine Laboratories (Dr. James Harvey and Hannahrose Nevins), Duke Marine Laboratory (Dr. K. David Hyrenbach), the Claremont Colleges (Dr. Cheryl L. Baduini), and US Geological Survey, Western Ecological Research Center (Josh Adams). Fieldwork would not have been possible without the dedicated support provided by numerous colleagues, and students and interns from Moss Landing Marine Labs. In addition we are working with Seaturtle.org to share our real-time data with the public via the WWW and with MBNMS to create rigorous, science-based curricula to enhance education for middle and high school students.

Project Sponsors

This project has received funding and support from the California Department of Fish and Game Oil Spill Response Trust Fund through the Oiled Wildlife Care Network at the Wildlife Health Center, School of Veterinary Medicine, University of California Davis, UC Santa Cruz, Tagging of Pacific Pelagics program, and the Monterey Bay National Marine Sanctuary’s SIMoN program. This research was approved by the SJSU Institutional Animal Care and Use Committee (#807), and conducted under CDFG Scientific Collecting Permit #6443.

** These are preliminary data. Please do not cite or distribute without permission from the authors