Ospreys taking a liking to San Francisco Bay

Although ospreys can be found worldwide, until recently there had been no record of their using the San Francisco Bay for anything other than wintering grounds. This nesting season, however, dozens of young ospreys took their first dives through the San Francisco Bay air and caught their first fish in its waters.

Ospreys go south for the winter and spend the breeding season in higher latitudes. In the past, they would pass up the San Francisco Bay to nest farther north. “If you look at the range route for ospreys now it looks like ospreys come down the Pacific coast and the nesting and breeding range stops somewhere just north of San Francisco,” said Allen Fish of the Golden Gate Raptor Observatory (GGRO).

But the osprey’s range is clearly changing. Ospreys are unique raptors in that they eat almost exclusively fish and so build their nests right along the waterfront. This makes their nests relatively easy to spot, and in recent years GGRO volunteers like Tony Brake have begun searching for and keeping a record of osprey nests around the Bay.

This osprey nest is atop a power line pole at Point Molate. Photo: Greenbelt Alliance.

“Tony called me up about a year and a half ago and said that they were doing pretty well finding osprey nests around the Bay,” said Fish. “I knew there were a few – maybe a handful – but I didn’t expect the number that Tony threw at me, which was fifteen in 2012.”

“We’ve had this increasing population for several years now,” said Brake, who along with fellow volunteer Harvey Wilson started an osprey census under consultations with the GGRO.

The first known nest along the Bay shoreline appeared on Vallejo’s Mare Island in 1990, and a single nest remained each season until 2003, when the population began to grow.

A decade later there are 17 successful nests around the Bay, with a total of 44 fledglings. The nests are concentrated at the mouth of the Carquinez Strait in Vallejo, but a few nests in Richmond were successful this year, as was one in San Francisco.

Osprey arrival

The parents begin arriving and building nests in late February, with incubation starting in late March. The first young hatch at the beginning of May, and in late July they begin fledging, or flying for the first time. The fledglings are currently honing their flying and fishing skills prior to their late-summer takeoff for their wintering grounds, likely in Central and South America.

The ospreys are usually not found on live trees as one might expect, but rather on top of dead, open-topped trees or on manmade structures like cranes and lampposts, which they find convenient platforms for their extensive nests. That makes this species one of the few that can adapt well to densely urbanized habitats. But trouble arrives when their real estate choices do not match the needs of humans. For example, one of the floating cranes parked at the closed Mare Island Naval Shipyard was removed early in the season, forcing the parents to abandon their nest. And earlier this season, the Port of San Francisco wrecked a nest that was perched on a crane that was needed to bring America’s Cup boats into the Bay.

Ospreys like nesting on top of manmade structures, like this ferry terminal in British Columbia. Photo: Keith Ewing.

Other feathery couples have been more fortunate. An osprey nest on a lamppost at the California Maritime Academy in Vallejo has been left alone. And Chevron went so far as to build a new nesting platform at the Richmond refinery when the old one became an obstacle to operations.

“It’s encouraging that [Chevron] put a platform up there to deal with it,” said Brake. “Hopefully, that will be an example for other organizations around the area.”

A CSI story

Experts are unsure why ospreys are suddenly taking to the Bay’s shores. “There are a lot of aspects to this,” said Fish. “It’s kind of an interesting CSI story.”

While all theories are currently highly speculative, there are quite a few possibilities. The Bay has grown clearer in recent years, the turbidity from the upriver placer mining of more than a century ago having finally settled, leaving the waters clearer and – likely – easier for ospreys to fish in.

Another thought is that the ospreys are spreading down from the Kent Lake colony in Marin, which was first noted in the 1960s and has since grown substantially. There are two parts to that particular theory; it may be that the ospreys are simply moving due to space constraints, but it is also possible that the recent appearance of nesting bald eagles at the lake may have upset the osprey population, inspiring its bay-ward move.

The theories go on. The recent ecological restoration of the Napa River may be playing a role. It is also possible that osprey populations from farther north have grown to such an extent following the ban of DDT that as they migrate over the San Francisco Bay they are choosing to stay.

Historical nesting grounds are in places like Lake Hennessey in Napa. Photo: John H. Wright.

Brake, Wilson, and the GGRO are currently working on a scientific paper to release the news of the Bay’s ospreys to the birding community; in return, they are looking forward to an influx of expert opinions.

“This is all pretty much speculation, so that’s a question that we’re hoping to get when we get the paper out there,” said Brake. “Some people that are fish experts and so forth might have some good ideas on that.”

Experts are hoping that once the paper is released, the accepted distribution of nesting ospreys will be extended to encompass the Bay.

Can ospreys coexist with humans?

The census will continue next year, but there are many unexplored scenarios as to how the human relationship with the ospreys might progress. Wildlife groups and companies like PG&E that deal regularly with ospreys will gather this month to discuss various interests, particularly how to protect the new population. As the ospreys return in coming years, experts hope to begin tracking some of them to determine where they go and if they return to the same nests. Fish also intends to promote raptor studies in the Carquinez Strait and to get more volunteers involved in order to identify and track osprey nests in the area.

In coming years, perhaps, the ospreys will take more strongly to other parts of the Bay, as the pair in San Francisco has.

“It’s exciting to think it’s not all about the Carquinez Strait,” said Fish. “Ospreys can handle San Francisco, they can handle the weird South of Market industrial areas down at Hunter’s Point that a lot of people have given up for industrial polluted areas and Superfund sites. To have an osprey there is an exciting symbol of ecological wellness.”

Check out this photo slideshow of a family of nesting ospreys on a Whirley crane at Point Richmond.

[slideshow exclude=88361,88364,88365]

Claire Mathieson is a Bay Nature editorial intern.

Warren Hall Implosion Reveals Secrets of the Hayward Fault

Saturday morning, an odd sort of earthquake occurred in Hayward — it came from the surface rather than the depths.

The seismically unsafe 13-story Warren Hall at California State University East Bay (CSUEB) imploded in what the United States Geological Survey (USGS) referred to as a “free” seismic source, a manmade earthquake that caused no unintended damage but that can be used to deepen our understanding of the Hayward Fault, that chthonic monster whose danger was responsible for the building’s preemptive demolition in the first place.

CSUEB’s geology department initiated the East Bay Seismic Experiment when it recognized the implosion as a great opportunity and contacted the USGS in Menlo Park with the idea of treating it as something rarely seen: a predictable earthquake. Scientists set about to carpet the area with temporary sensors, installing more than 500 around the makeshift epicenter. They were placed anywhere from vacant lots to people’s front yards and were primed to detect the controlled earthquake. The information the sensors collected will be used to further investigate the nearby area of the Hayward Fault, which is overdue for a large quake.

http://www.youtube.com/watch?v=QuXY8F85sYs

The implosion – as would an earthquake – sent waves radiating through the earth, which will allow geologists to map the local section of the fault. The waves act much like sonar, constructing a picture of what lies beneath. They change their behavior depending on the material through which they are traveling, with high-density materials transmitting waves more quickly than low density ones. Because the atoms in high-density materials are closer together, they can transmit the energy more quickly. In this case, faster waves indicate solid, more stable bedrock, while slower ones indicate loose sediment, which is more unstable and more prone to intense shaking. Geologists can get a sense of the subsurface structure based on when the waves arrived at the various sensors. This could allow scientists to predict which areas of Hayward will be most subject to violent shaking in the next large earthquake.

Seismic sensor for Warren Hall demolition. Photo: Yousuf Fahimuddin.

This method of using waves as a window into what can’t be seen is not new; in fact, geologists used it to discover the crust-mantle-outer core-inner core model of the Earth’s interior that placed Journey to the Center of the Earth firmly in the realm of fiction. Now the method is expected to allow scientists to determine not only the underlying materials but the structure of the fault itself, including whether or not it connects to parallel faults. Because a fault typically separates different rock or soil types or contains a thin layer of distinct material – often clay or ground-up rock formed as the two fault blocks scoured each other – waves can change paths or speeds in the fault zone as they move through the anomalous layer. This wave behavior should cause the buried fault zone to light up in the results.

A model of our Earth's interior as determined by the behavior of seismic waves. Photo> Creative Commons. — A model of our Earth’s interior as determined by the behavior of seismic waves. Photo: Creative Commons.

Not only should the experiment allow scientists to map part of the Hayward Fault, it could also help make the Bay Area’s regional earthquake-monitoring network more accurate. Scientists will look into how well the network pinpointed the implosion and – if necessary – will adjust the regional seismic network to improve its performance for the future.

It may come as a surprise that our knowledge of this notorious fault is limited, but this attests to the unique nature of the experiment. Implosions for research purposes are far too costly, but in this case the necessary factors fell into place perfectly. A building adjacent to the Hayward Fault was in need of demolition and conveniently located on a college campus where geologists would notice it. The threat of an earthquake brought Warren Hall to the ground, but hopefully the building’s sacrifice will diminish that threat, helping us prepare for the temblor that cannot be controlled.

Claire Mathieson is a Bay Nature editorial intern.

Whales in danger of ship strikes gain mobile app

It’s been a promising season for whales migrating around the waters of the San Francisco Bay.

For one, food is plentiful because of a massive krill bloom, which is bringing them close to shore. There’s normally danger involved when they enter coastal shipping lanes, but the whales are more protected than ever this summer due to new regulations on ship navigation through whale territory around the Golden Gate.

And last week saw the release of a mobile “spotter” app, which allows users (mainly intended for boat captains) to pinpoint real-time whale locations on a map, a feature that will create a registry of whale sightings that can be used to further adjust shipping lanes in response to whale densities.

Conservationists hope that the new app — available in the App Store as Spotter Pro — will help protect whales in cases where the regulations may not. The new lanes have been narrowed in some places and extended in others to avoid areas known to be frequented by whales. However, the lanes are now immovable until their reassessment by the U.S. Coast Guard. The whales, of course, will continue to venture where they please, heedless of the human thoroughfares.

Hundreds of ships travel through the bay each year, posing a serious risk to whales in their path. Photo: Gareth Jones/Flickr

With the spotter app, a user can record the location of their whale sightings and any relevant behaviors and photographs. The app uses a device’s GPS to capture the exact location of the sighting and can also catalog weather, sending all information to a cloud database.

“It’s really our eyes and ears on the water,” said Michael Carver, Deputy Superintendent for the Cordell Bank National Marine Sanctuary (CBNMS).

Conservation groups like CBNMS intend to use the data to create dynamic management areas. If the spotter app shows whales in a particular traffic lane, conservationists will go out to verify the sighting, and ships will be asked to slow down or reroute to a different lane. Ship cooperation will be voluntary at first, but if vessels do not change their behavior in accordance with the recommendations, their response will be made mandatory.

“We’re looking at creative strategies to change the distribution of vessels based on real-time information about where the whales might be at any given time,” said Leslie Abramson, a resource protection specialist with the Gulf of the Farallones National Marine Sanctuary (GFNMS).

Fortunately, shippers have been on board with the new regulations and have cooperated with regulators and conservation groups. The Pacific Merchant Shipping Association (PMSA) has contributed funds to the development of the app and has helped create educational posters for ships to familiarize crews with whale species and reporting methods.

“They have been really cooperative,” said Abramson. “They absolutely love those animals as much or more than any of us landlubbers.”

PMSA’s vice president John Berge said shippers have an important role to play, given their maritime vantage point.

“Ships have the potential to serve as platforms for spotting and reporting whales on the coast, since they are traveling those routes as a matter of course,” said Berge.

Landlubbers, too, can contribute to the effort by donating old iPhones through the mail to those who can be of most help, like ship captains. And everyday citizens at sea, say, on sightseeing trips, can record whale sightings by downloading the app as a “demo” user.

A humpback whale breaching in the Gulf of the Farallones National Marine Sanctuary. Photo: NOAA.

“It’s sort of akin to a Twitter feed,” said Carver. “It might not be the most precise information, but it’s a nice pulse on what’s going on out there.”

At this early stage, it’s hard to say how many ship strikes might be avoided with the spotter app, but those involved in this crowdsourcing project believe it will ultimately lead to a decline, especially as more people participate.

Carol Keiper, a marine ecologist with the conservation nonprofit Oikonos Ecosystem Knowledge, has been field-testing the app since March.

“I love using this spotter app,” she said. “Instead of spending so much time writing the data and then entering it on my computer in a database, all I need to do is tap, tap, tap.”

Claire Mathieson is a Bay Nature editorial intern.