NPS staff measure water quality parameters throughout Bay Area parks. Credit: NPS Photo.

Point Reyes National Seashore staff undertake many research projects each year, such as studying tule elk and monitoring harbor seals and other pinnipeds that haul out on the beaches. However, Seashore researchers do not operate in a vacuum. Both the Pacific Coast Science and Learning Center (PCSLC) and the San Francisco Bay Area Inventory and Monitoring Network (I&M) conduct or coordinate research throughout many of the parks in the region, including Point Reyes National Seashore, Golden Gate National Recreation Area, Pinnacles National Monument, and Muir Woods National Monument.

Some current PCSLC and research partner studies include Seafloor Habitat Mapping, Coastal Biophysical Inventory, and Fungal Biodiversity Inventories. The National Park Service also conducts long-term monitoring of critical natural resources. Much like a doctor measures blood pressure and body temperature to assess health, the I&M program tracks a suite of high priority ecological indicators as a way to measure the health of the parks.

These ecological indictors fall into four major categories:

Air and Climate

Scientists evaluate weather, climate, and air quality parameters to support understanding of local climate change and to alert staff and visitors about potential exposure to air pollution. Parameters include temperature, precipitation, ozone concentration, and visibility.

Water

Researchers measure water quality and quantity parameters to identify pollution sources, to ensure NPS meets minimum water quality standards, and to make certain that enough water is flowing through the stream to support the requirements of threatened and endangered species. Parameters include pH, dissolved oxygen, water temperature, indicator bacteria, and flow.

Ecosystem Patterns and Processes

Researchers assess landscape vegetation and land use to evaluate changes and demonstrate the importance of park land in a rapidly urbanizing landscape.

Biological Integrity

Flora: Researchers identify the need for wetland and riparian habitat restoration by measuring extent, type, and species composition. Researchers also study species diversity in plant communities and detect invasive plants to develop priorities for habitat management and restoration as well as eradication of invasive species.

Fauna: Researchers monitor a variety of animal species, including those threatened and endangered, to identify habitat protection and restoration needs and to recommend management efforts. The monitored species comprise coho salmon, amphibians and reptiles, landbirds, western snowy plover, northern spotted owl, raptors, and pinnipeds such as harbor seals.

For more information, visit http://science.nature.nps.gov/im/units/sfan/science_in_parks.cfm.

Development near Limantour Beach in 1961. From NPS Archives.

Before Point Reyes National Seashore received protected status from the federal government, the area was privately held. Ranching operations began in the 1800s, followed in the 1950s by residential development near Drakes and Limantour Esteros. Naturally, this development brought along with it infrastructure – roads, dams, and culverts, among other things. Concern over the development and a desire for public coastal access led directly to the establishment of the Seashore in 1962. The Seashore continues to remove what legacy structures it can in an effort to provide a natural place for fish and other wildlife, as well as its human visitors. In 2006, the Seashore received $2.44 million in federal funding to undertake some of this coastal watershed restoration, and many of the projects were recently completed.

Dam Removal

A beach access berm was built at Limantour Beach in 1952, and Muddy Hollow Creek was dammed in the early 1960s to create a recreational pond for a proposed residential development. These dams obstructed tidal dynamics and fish passage for the federally threatened steelhead trout, and dramatically affected natural processes and habitat.

The National Park Service removed both of these dams to return the tides to more than 15 acres of coastal marsh habitat in the Estero de Limantour. Tidal influence provides everyday renewal of the sort created by a freshwater flood event. Smolting steelhead that researchers found in Muddy Hollow Creek prior to dam removal can now get to the ocean, and vegetation is changing from freshwater species to saltwater species, including pickleweed and cord grass. The freshwater/estuarine transition zones will also be able to shift with anticipated changes due to sea level rise.

As part of this project, the National Park Service rerouted Estero Trail, which used to follow the crest of Muddy Hollow Dam. They also replaced the beach access berm with a bridge to provide continued visitor access.

The old beach access path on top of a large berm. Credit: NPS Photo.

The new beach access bridge, allowing tides to flow beneath it. Credit: NPS Photo.

Road Crossing Replacement

Although roads are still needed throughout part of the Seashore, many of the structures associated with roads are outdated. Historically, road crossings over creeks were designed without regard to fish passage, preventing anadromous fish from moving freely and interfering with their life cycles.

The National Park Service removed two road crossing culverts that prevented fish passage on East Schooner Creek and replaced them with bottomless arch culverts. The old culverts resulted in three to five foot vertical drops, a major impediment to fish passage, and frequently overflowed during floods. The new culverts feature a natural streambed bottom that can adjust with changes in the adjacent streambed.

These culvert replacements decrease the risk of structural failure, reduce long-term maintenance needs, enhance habitat for federally threatened steelhead trout – allowing them to migrate freely from freshwater to ocean and back, and allow for the reintroduction of federally endangered coho salmon. They may also accommodate larger storm events that may result from a shift in natural variability as a result of climate change.

For more information about these and other coastal watershed restoration projects, please visit: http://www.nps.gov/pore/parkmgmt/planning_cwr.htm.

Thanks to Point Reyes National Seashore’s Web master, Chris Lish, you can now easily find The Natural Laboratory Podcast on iTunes and download episodes to your iPod. Subscribe via the RSS feed at Point Reyes multimedia Web site. You can click on the RSS button, or copy and paste the address into iTunes or your own podcasting software. Or, if you prefer, look us up in the iTunes Podcast directory. Searching for “Point Reyes” usually does the trick.

Click here for a special preview of our latest auditory journey, visit the Bay Model with Pacific Coast Science and Learning Center reporter John Cannon, and learn about science at parks in the San Francisco Bay Area Network.

Photo by John C. Cannon

Eager to learn more about the science happening at San Francisco Bay Area National Parks? Follow the struggle of the endangered coho salmon as biologists fight to revive the population in Redwood Creek at John Muir National Monument. Explore internship and volunteer opportunities for all ages at national parks in the region. And discover a massive inventory project that has recently cataloged some 161 km of coastline in northern California.

The current Parks for Science newsletter covers all this and more. Visit our Web site to view past issues.

A white shark takes an exploratory bite of a seal-shaped decoy. Image by Taylor Chapple.

Journey with the Natural Laboratory to the waters around Tomales Point, and join a team of shark researchers as they search for one of the ocean’s great predators. White Sharks of the Northern Pacific (7:09 minutes)

To follow fish biologists into the field and discover evidence of ancient tsunamis at Point Reyes National Seashore and other San Francisco Bay Area National Parks, visit the home of the Natural Laboratory Pocast.

On a clear day, Drakes Estero and Abbotts Lagoon can be seen from the top of Mount Vision. Image by John C. Cannon.

Dealing with the invasion of nonnative species is a central focus of many biologists at Point Reyes. Bullfrogs, mosquitofish and iceplant, to name a few, have wormed their way into ecosystems in the park, exploiting niches where they can beguile unacquainted potential predators and outcompete their native counterparts in the contest for resources.

And while many populations of these interlopers are well established, others are still revealing themselves during routine diversity and inventory studies undertaken by park scientists.

As these small populations crop up, says restoration biologist Ellen Hamingson, it’s important to nip the problem in the bud—quite literally in this case. To control invasive populations before they get out of hand, “we look for things we know are invasive, but are now low in abundance,” she says.

Native to Europe, sweet vernal grass was discovered near the peak of Mount Vision this summer. Image by Lindsay Herrera.

On a routine survey this past summer, biotechnician Melissa Potter discovered a smattering of sweet vernal grass, an invasive species from Europe, for the first time in the park on Mount Vision, northwest of the visitor center (view a video on the importance of vegetation mapping here). Though park scientists don’t shy away from large-scale projects—a multi-year project is currently underway involving heavy equipment and hundreds of volunteer, contractor and staff hours to root out prolific iceplant from nearly 200 acres of parkland surrounding the lighthouse—an early investment to remove this small, isolated population of sweet vernal grass could obviate the need for more drastic measures down the road when the incursion might become more serious.

So Hamingson and Potter organized a work trip to confirm the locations (by GPS) of the sweet vernal grass on Mount Vision and to remove as much as possible. As with many park projects, volunteers were a big part of the plan. But because this particular invasive species was only sparsely present among other types of native grass, they couldn’t just ask their helpers to slash through a bunch of vegetation without regard for what they were destroying.

Fortunately, the “weed warriors,” as they call themselves, who came to the slope of Mount Vision that day “weren’t your typical volunteers,” says Hamingson. Hailing from the eastern shores of San Francisco Bay, the women were members of the Friends of Five Creeks organization. In addition to looking out for water quality, greenspaces, and native species in “urbanized” East Bay through a host of hands-on volunteer projects, members of Friends of Five Creeks foray beyond their stomping grounds to take on problems in other areas.

Distinguishing sweet vernal from the myriad other grasses on Mount Vision required skill and experience, but should be easier in the spring. Image by Lindsay Herrera.

Their expertise in identifying pernicious nonnatives proved invaluable to Hamingson and Potter. The group spent the morning hours teasing out sweet vernal grass from the vegetation abutting Mount Vision Road, searching for the brown seed heads that are subtly darker than those of surrounding species in the early fall. They also removed massive clumps of purple velvet grass, another invasive nonnative. Populations of this species are so pervasive that it’s not actively managed in the park, Hamingson said, but removing it along with the sweet vernal would cause no harm.

Shortly after a lunch break, the team attacked one of the probable points of initial growth–a brushy area, just a few meters off the road where beds of the dark golden grass grew thick. Staging this initial removal was the first step in trying to keep sweet vernal grass under control at Point Reyes. Members of Friends of Five Creeks have pledged to return in the spring, when the seed heads are green and easier to identify, to take the next step in stamping out sweet vernal grass.

Guest Post by Morgan Gilmour and Sandy Rhoades, Common Murre Restoration Project

It’s 7:30 AM and we, the two Point Reyes seabird biologists, have just descended all 308 Point Reyes Lighthouse stairs, carrying telescopes, tripods, notebooks, maps, cameras, and binoculars.  We enter the equipment building next to the lighthouse, and set-up shop in a small room near the old diesel generator.  A gust of wind rushes into the room as we slide open the west-facing window with a high pitched screech.  It’s going to be another freezing, windy day inside the lighthouse.  But, at least it’s not foggy.  With wind, at least we can see the birds on the rock below.

Morgan Gilmour with a spotting scope; Image by S. Rhoades

We quickly grab more layers of clothing to fight the wind, including down jackets, scarves, winter hats, and gloves.  We are now prepared to stand in front of this open window for the next five hours.  The date today?  June 14th, the middle of Common Murre breeding season.

We wedge two tripods into this one window.  Atop each tripod sits a high-powered Questar telescope.  We adjust and focus our telescopes until we are correctly aimed at the rocks directly below us, several hundred feet down.  Perched on the rock are thousands of black and white birds, strangely resembling penguins.  These birds huddle together, most so close to one another that it’s hard to tell where one bird ends and another begins.  There are about 16,000 pairs of murres breeding just offshore on Lighthouse Rock.

Murres at Lighthouse Rock, Image Courtesy of S. Rhoades

These birds are Common Murres, and actually not related to penguins.  Murres belong to a group called alcids and are more closely related to puffins than to penguins (alcids also include murrelets and auklets).  Like penguins, alcids swim through the water using their wings, but unlike penguins, they can fly.   Murres weigh about two pounds, and are about the size of a football.  They aren’t the most graceful flyers, and flap their wings as they run along the water to get a head start before lifting off.

Murres are seabirds that spend most of their life on the water, and come to land for a few months during the summer to breed. It is June now, and the murres have their breeding season in full swing.  Most birds are incubating eggs, ranging in color from white to bright blue or green, speckled with brown spots.  Murres don’t bother building nests, but lay their one egg directly on the rock.  The male and female will take turns incubating for about 30 days before the egg hatches.  Some of the eggs have begun to hatch, and little black and white balls of fluff can be seen throughout the colony, sitting at their parents’ feet.

Our job here is to watch a section of this huge rock, and “take attendance” of each of the birds sitting in this section.  We record which birds are here and which have eggs or chicks.  We keep track of these birds through the season and from year to year.  Murres typically return to the exact same spot on the rock each breeding season.  We have photos of the sections of rock, with numbered nesting sites.  We use this “map” to follow the breeding success of the Murres in each plot. This can be frustrating work.

Murre with Egg, Image by Common Murre Restoration Project

One of us monitors “Edge Plot” and the other takes “Ledge Plot.”  Edge only has 62 breeding sites, and Ledge has over 80.  Edge Plot is along an edge of the colony where younger birds tend to set up territories, while Ledge is in the middle of the colony where the nesting sites are more established.  Murres don’t begin to breed until they are 4-6 years old, 4 and 5 year old birds may spend a couple years prospecting and establishing territories before laying eggs.

We start going through the attendance sheet:  “1, 2, 3, and 4 are here, but I can’t see 4’s egg!”…a few minutes later…  “Wait, I think #4 hatched!  I see a little fuzz ball moving!”

Murres are social birds, living in close quarters with one another on the rock.  Once their eggs begin to hatch, all the murres seem to get excited about having cute little chicks around. Sometimes a murre without a chick may “baby-sit” a chick from a nearby site; this can make things very confusing for us researchers!  Baby-sitters are often birds that lost their eggs earlier in the season. They may also be younger, inexperienced birds who are gaining experience with chicks by baby-sitting, or kin helping to raise their relative’s chick.

Murre Chick; Image courtesy of Common Murre Restoration Project

“Number 133 has a chick?!?  Where did that come from?  He never even had an egg!  Oh, wait, 133 must be baby-sitting for 35!  Yeah, now I can see 35, and there is nothing at his feet.”

“That’s 104, and there’s 98, and next to 98 is 121… where did 140 go?  Can I see the map again… Oh no, I think 140 is missing!  140 must have lost its egg.”

Murres are attracted to areas where other Murres hang out.  Even if they aren’t breeding, Murres will often sit in spots on the rock with other birds, and act like they are incubating eggs.

“Ugh, I’m still waiting to see 102’s egg.  He’s facing the rock, and won’t turn this way!  Oh, wait!  Fight!  A bird just came flying in with a fish and landed on top of a bunch of other birds.  They’re all pecking at it as it’s scrambling to get to its spot.  It’s climbing on top of their heads… now another bird is pecking at it, and it flew straight into 102!  102 turned around!  He has a bright green egg!  Finally!  We’ve been waiting for three weeks to confirm that he is actually incubating an egg!”

Murre with egg; Image courtesy of Common Murre Restoration Project

We stand in the window, bracing ourselves against the strong northwest wind, as the tripods and telescopes shake from the wind, trying to make sure that we see each and every bird and their egg or chick.  Most days, this takes several hours.

Do we do this everyday?  Pretty much, but when we’re not in the lighthouse monitoring murres, we have plenty of other work with seabirds to do in the Point Reyes Headlands.

Once a week, around 10:00, we take a break from monitoring the murres, and count them instead.  We focus the Questars on each of the rocks and sea stacks that line the western half of Point Reyes Headlands.  Other species breed here too including Brandt’s and Pelagic Cormorants, Western Gulls, Black Oystercatchers, and Pigeon Guillemots.  Brown Pelicans and Heermann’s Gulls, also roost on these sea stacks.  We count all of these other species on each of the rocks near the lighthouse, and then pack up, climb back up the 308 stairs with our telescopes, tripods, notebooks, maps, and cameras, and hike to other cliffs on the Headlands where we can see the other offshore rocks and continue our count.

While out here at Point Reyes, we also monitor disturbance to the birds.  Ravens, vultures, and pelicans can disturb murres and cormorants, causing egg and chick loss.  People, aircraft, kayaks, and fishing boats can also disturb birds by approaching too close to their rocks.

Why do we work out here in the wind and fog?  The Point Reyes murre colony is one of the more established colonies on the California coast.  By monitoring the numbers of birds on the rocks, the number of eggs that are laid, and the number of chicks that hatch and survive, we can get a good idea of how the murre and other seabird populations are doing from year to year.  Seabirds also act as indicators of the health of the ocean ecosystem, so the data we collect can give us insight into a much bigger picture of what’s going on in our ocean.

Two Common Murres on Water; Image by S. Rhoades

A couple of big oil spills have impacted murre populations and prompted the beginning of the Common Murre Restoration Project and our efforts to restore, monitor, and protect murres and other seabirds nesting here along the coast.  Our monitoring efforts give us an indication of how well the murre populations are recovering from these spills, and help to reduce other human caused disturbance to nesting seabirds.

Next time you’re out at the Point Reyes Lighthouse, take a moment at the observation deck before heading down the stairs.  Glance down at the big rock closest to the lighthouse.  From April to July you’ll see this rock packed with thousands of breeding Common Murres.  On a calm day you can even hear their murre-murring drifting up from the rock below.

Imagine jumping into a washing machine, filled with rocks and icy water, and setting it on the spin cycle. Give yourself a few hours in those conditions before running outside and laying on the asphalt during a heat wave. Repeat. This is an everyday occurrence for those remarkable organisms who call the intertidal zone home.

On the west coast of North America, the intertidal zone spans a height of about eight feet, which is the extent between high and low tide. Just eight feet! And yet this predictably precarious margin of damp rocks and turbulent surf is the only place on Earth that many organisms call home.

The boundary between surf and turf is a rich landscape, offering many rewards to those who are hearty enough to live there, but life here is not easy. In a matter of hours, a parched and baking landscape shifts to a seascape where frigid and unforgiving waves take control.

So, what does it take to live in such a wild location? It seems that most organisms interested in taking up residence take one of two approaches: be tough or be flexible.

The Tough Guys
When faced with battering surf, threats of dehydration and countless creatures looking for an easy lunch, a common adaptation in the intertidal zone is to be tough and don some armor. Many creatures take measures to protect their bodies by having a sturdy protective boundary in the form of an exoskeleton or shell: crabs, barnacles, urchins, snails, limpets, chitons and mussels.

Among the armor clad one of the most steadfast is the mussel. These bivalves are currently being studied by medical researchers who are curious to know how they’re able to stick so, well, stickily to the rocks, despite incredible pressure from wave action. It turns out that the mussels are always reinforcing their connection to the rock they call home. As the tide comes in and they’re covered by water the mussel will extend its foot and mend its connection to the rock by producing incredibly powerful strands of protein that appear to the casual tidepooler as hairs. The possibility of studying this remarkable adhesive power and using it for medical purposes is really quite exciting.

As ingenious as the mussel is and sticking to rocks, it can’t always evade the hungry sea star.

Ochre sea stars lounge on top of their would-be lunch

Sea stars, a sturdy yet flexible predator, are the tigers of the intertidal zone. When a sea star finds a mussel that seems like it will make a sufficient lunch, it will use its thousands of feelers to cling to the bivalves shell. Then it pulls. The sea star doesn’t need to pull the shell very far apart, a crack will do. Once an opening has been created, the sea star does something extraordinary: it inverts its stomach. Yep, the sea star will actually push its own stomach into the opening it has made. Digestive processes then go to work, turning the mussel into delicious slurry that the sea star can then take back into itself.

Flexible Fellows
Some organisms survive the onslaught of the tidal zone by literally going with the flow: alga, sea grasses, sponges, anemones, nudibranchs and octopi. Their supple tissues respond to the impacts of the ocean with ease. For these organisms, the main threat doesn’t come from being battered to pieces, but from drying out–and being eaten of course.

The anemone solves both of these problems. For the hours between low and high tide, when the threat of dehydration is paramount, anemones are remarkably good at holding onto water. They do this by folding in on themselves, thereby reducing their surface area and opportunity to lose water. Anemones can also be quite adept at cloning themselves. If the threat of being gobbled up is high, it is certainly advantageous to make more than one copy of yourself. In some parts of the intertidal zone, you can find whole rocks simply covered with sea anemones that are all clones of one individual.

Sea anemones are filter feeders and use their tentacles to catch food as it drifts by

Then there’s the nudibranch. Nudibranchs, sometimes called sea slugs, are the rock stars of the tidepool. It has been said that if the Las Vegas strip were a slug, it’d be a nudibranch. These gastropods come in a wide variety of wildly bright colors and patterns with all manner of strange fronds dangling from them. But these critters aren’t just flashy in appearance, they’ve got style too. A nudibranch can actually eat the arms off a sea anemone, digest part of it, but save the nematocysts (the stinging cells) for another purpose entirely. These astounding creatures actually take the nematocysts, transport them to their skin and repurpose them as stinging cells on their own back. This is roughly equivalent to you swallowing a baby porcupine and then growing quills on your back. Some nudibranchs have also been known to repeat this process with chloroplasts from plants.

Of course, not all organisms that rely on the intertidal zone live there full-time. Birds, foxes, raccoons, bears and humans all happily enjoy the bounty of food found in the intertidal zone. In fact, there’s a saying in virtually every indigenous coastal community that translates to, “When the tide is out the table is set.”

As bountiful and mysterious as the intertidal zone is, it’s easy to image it standing up to anything life throws its way. But the fact is that the intertidal zone is a delicate place that is very susceptible to changes in climate and environmental quality. It’s for this reason that scientists along the entire California coastline are actively engaged in monitoring the intertidal zone over time. As we gather information about what species call the intertidal zone home we’ll be better able to see how this changes over time and what factors are involved in the change. This is a crucial practice if we are to preserve this outstanding ribbon of life that exists where the land and sea intertwine.

The beaches at Point Reyes National Seashore are home to many creatures, but only one bird uses this fragile system to nest, the Western snowy plover, a bird that people rarely see.

A full grown adult of this threatened species could fit inside a person’s hand and most people could walk right over the nest of a snowy plover and never see it. This is part of the problem.

Kate Peterlein, a long time Point Reyes resident, has been managing the Western snowy plover monitoring and recovery program for the Point Reyes National Seashore since 2001. If you were to walk the beach with her, you would see nests, birds, and a tenuous future for such a small creature.

Each day she walks the beach finding the birds through her binoculars, counting them and observing the struggling population. The strong winds this year have made this nesting season particularly hard for the plovers.

Western snowy plovers, build their nests directly on open sand. They lay three small speckled eggs in a depression called a scrape. When snowy plovers pair off to breed, the male begins by making a scrape. If the female approves then the pair starts a nest. If the female doesn’t like the location, then the male makes another scrape. “A male could make one scrape or twenty,” Peterlein said. “It just depends on if the female likes the spot.”

The female picks a spot and she lays three eggs over the course of a few days, but she does not start incubating until the last egg is laid. This is why Peterlein walks the beach every day. It is essential for her to be able to find the bird’s nests before ravens or other predators do. “If we miss a nest, we will likely lose it,” Peterlein said.

When Peterlein locates a nest, she assembles a cage around it called an exclosure. An exclosure is the opposite of a trap; it allows the plovers to come and go, but it keeps out predators. Ideally they are assembled when the first egg is laid to prevent egg loss to predators and disturbance to adult plovers.

Plovers incubate their eggs for almost a month. They are egalitarian when it comes to incubating their eggs. Males and females each sit on the nest half the time, switching duties at sundown and sunrise. When the pair switches incubating duties, there is an elaborate routine involving tail fanning, and tossing pebbles. “It is almost like they are saying to each other: Hi honey, I’m home,” Peterlein said.

When the eggs hatch, the plover chicks explore the world under the watchful eye of their father for almost a month. Like many ground-nesting, birds these tiny chicks are able to walk upon hatching. “You see this little golf ball with fur on it and toothpicks for legs running around,” said Eric Stearns, the park Service ranger coordinating the outreach and education portion of the project.

Stearns coordinates the volunteer snowy plover docent program at Point Reyes. The program teaches volunteers how to talk with visitors about sharing the beach with the nesting plovers.

“Plovers are a resource that is very tough to interpret,” Stearns said. “They are not like tule elk or elephant seals because most visitors will never see this species. Plovers are a resource critical to protect but very hard to share with the public. Because plovers rely on camouflage for protection, the very nature of these small birds provides for challenging observations.”

People and pets on the beaches can disturb nesting plovers. So, on weekends during the summer, volunteers help visitors understand how to maximize their enjoyment of the seashore while also giving snowy plovers a chance to survive. By 2 p.m. the Sunday before Memorial Day, the two volunteer docents, Frank Binney and Jennifer Tripp had talked to more than 100 visitors at the Abbott’s Lagoon trailhead. By educating visitors about closures and offering suggestion as to how best enjoy the beach without disturbing birds, visitors to Point Reyes National Seashore are given the opportunity to help this threatened species survive.

The docent program was started to decrease the number of chicks lost during weekends due to human disturbance. Looking at the numbers, Binney said the program is a success. Chick loss on weekends has decreased significantly since the program was instituted.

“We teach themes,” said Binney, who has been volunteering in the park for 12 years. “Sharing the beach with wildlife means we can all enjoy the beach with a little consideration. It is win-win.”

Protecting these birds is part of the National Park’s mission, but these birds are more than just a natural resource to the people who work with them. “It is a hard job working really close to a species struggling as much as this one,” Peterlein said. After eight years of working with a team at Point Reyes, Peterlein is sure the effort is worth it. “It is really emotional, but there is great satisfaction helping restore native species.” With the help of vegetation ecologists who are coordinating a coastal ecosystem restoration to provide more habitat for plovers and volunteer outreach docents, snowy plovers nesting at Point Reyes National Seashore are being given the chance to survive in their native habitat.

(This is a guest post by Jessica, reprinting her latest Point Reyes Ocean Update. To subscribe her Point Reyes Ocean Update, email jessica_luo {at} partner.nps.gov)

Have you ever seen a white shark at Point Reyes? How about one feeding on seal carcasses near the headlands? Would you like to know where and how often white sharks are seen, and what they are usually seen doing? This may be useful information if you dive or surf in open water here!

Scot Anderson, Ben Becker and Sarah Allen published an article in the January 2008 edition of California Fish and Game on observational sightings of white sharks at Point Reyes National Seashore (PRNS) over 23 years and decoy surveys over 11 years.

 
A white shark is seen here feeding on a seal just off shore. Photo credit: S. Anderson, 2007.

Where are they seen? Most observations were clustered in three areas: Point Reyes Headlands, McClures Rock, and Tomales Point. White sharks are mostly seen close to shore, in water depths from 5m to 30m. This is likely because they need to keep sight of the surface where they capture their prey.

When are they seen? White sharks are observed at PRNS most frequently in the late summer and fall (August, September, October), which coincides with the seasonal peaks of pinnipeds: California sea lions congregate in the area when males migrate north in the fall, and northern elephant seals juveniles haul out in the fall. When Scot Anderson used decoys to track the frequency of white shark appearances, he found that they were seen approximately once every 6 hours at PRNS! However, this frequency is still less than the frequency in which they are sighted at the Southern Farallon Island: once every 1.9 hours.

What do they eat? At Point Reyes National Seashore, white sharks prey on pinnipeds that congregate onshore and they also scavenge on marine mammal carcasses (especially whales). At the Farallones and Año Nuevo, the pinniped population that white sharks primarily feed on are the northern elephant seals. However, this is not what Scot Anderson found at Point Reyes—the white sharks here seem to be feeding mostly on harbor seals and California sea lions.

White sharks also scavenge off of marine mammal carcasses. Large dead marine mammals such as sperm whales, baleen whales, and northern elephant seas can leave an odor trail that can be carried for many kilometers. White sharks can track these “odor corridors” and follow them to the source. In 2004, when a dead sperm whale drifted to PRNS, as many as four white sharks came to feed on the carcass at one time. A large white shark (~943 kg) can survive up to 45 days after feeding on 30 kg of blubber from a dead cetacean!

Should I be concerned about attacks on humans? There has been five human attacks by white sharks at PRNS over 23 years, all of which occurred in the fall season close to shore in water <10 m deep. All the victims survived. Those highest at risk appear to be people who dive for abalone, spearfish, or surf in open water in or near areas where sharks have been sighted, or near seal colonies. Please be careful, and report any white shark attacks to a park ranger (415-464-5170).

If you would like more information on white sharks at Point Reyes, Scot Anderson can be reached at sharkman1137 {at} mac.com