“Is there WiFi around here?” You’ve probably heard that one in the airports this holiday season.
The modern traveler is forever looking for wireless internet hotspots. But constantly wandering predators like the sooty shearwater (Puffinus griseus) -- a relative of the albatross that breeds on islands off Chile and New Zealand -- are drawn to abundant food and "foraging hotspots" during the boreal (northern) summer along the west coast of North America.
Shearwaters naturally find these feeding grounds, but they’re not so apparent to biologists who want to map these hotspots to improve marine conservation planning. By attaching satellite transmitters to the shearwaters, however, biologists can now map shearwater movements and figure out where these foraging hotspots occur.
“We hypothesized that the birds were responding to certain environmental cues in a search for feeding opportunities throughout the California Current System,” says USGS scientist Josh Adams, who works in Santa Cruz, California, as part of the WERC San Francisco Bay Estuary Field Station.
With funding assistance from California Sea Grant, Adams and his colleagues Dr. James Harvey and graduate student Melinda Nakagawa of Moss Landing Marine Laboratories attached satellite tags to 57 shearwaters in the waters off Santa Barbara, Santa Cruz and the Columbia River Plume off Washington.
Having tracked the birds during the spring and summer months since 2004, Adams says an interesting picture is emerging.
|This map of the California coast shows the locations where sooty shearwaters frequent. The areas in red are the "hotspots" highly used by shearwaters, while the areas in blue are low-use areas. Map courtesy of Josh Adams/USGS
“The shearwaters definitely congregate over certain areas,” says Adams. “But it looks like these feeding hotspots can change from year to year, possibly due to changing conditions in the currents.”
Decadal ocean climate patterns, more frequent El Niño events and temperature shifts are known to influence wind-driven ocean upwelling and nutrient conditions along the California coast. These in turn can change the locations where nutrients and fish prey are likely to accumulate.
The migratory shearwaters -- unlike resident breeding birds which must stay near fixed colonies -- presumably follow these shifting hotspots.
“These guys are the frequent fliers of the animal world,” says Adams. “It’s amazing to piece together the travel routes of individual birds into a cumulative map of where this species likes to hang out.”
One revelation is particularly of interest to resource managers: satellite data show that shearwaters only spend a quarter of their time foraging within National Marine Sanctuary waters, which are intended as our nation's system of marine protected areas, to conserve, protect, and enhance biodiversity, ecological integrity and marine cultural legacy.
Adams has worked with numerous other species throughout the Pacific and currently is developing computer analysis tools to discern animal movement patterns that are tied to the changing ocean environment. Continuing questions include whether commercial fishing impacts these feeding hotspots and forces birds to find new ones, and where protected areas can be best drawn to balance both conservation and economic interests.
-- Ben Young Landis, with additional reporting by Rebecca Buddingh of California Sea Grant
Top: With a wingspan of around 36 inches, sooty shearwaters can nevertheless fly over 5,000 miles from breeding grounds to foraging grounds -- that's about a fifth of our planet's circumference. Image credit: Josh Adams/USGS.