Howdy, Birders,
Recently, birders along the Central Coast of California have reported large streams of SOOTY SHEARWATERS swirling and moving along the shore. Birders are wondering why this is happening. Perhaps this blog post will offer some explanation.
SOOTY SHEARWATER, Monterey Bay, California
Image, copyright, Beth Hamel.
Even though large flocks of Sooty Shearwaters are often seen, their worldwide population has DECLINED 90%! They, along with Short-tailed, Flesh-footed, and Streaked Shearwaters are in steep decline.
Everyone is talking about EL NINO
and the massive warm water bodies offshore in the Pacific Ocean and off California. Indeed, the Monterey Bay Weather Buoy recorded a record-breaking 69F Sea Surface Temperature at 2 pm PDT on August 12, 2015.
The Monterey Weather Buoy is the red dot in the Terrafin image, below.
While the report of this record-breaking SST is incredible, it does not tell the whole story.
The ocean, and even so-called, bays such as Monterey Bay, is a dynamic, ever-changing habitat.
Winds and currents greatly affect the sea surface temperature (SST).
Looking at the August 13th SST chart, above. we can see that the nearshore areas are blue, and some are a very deep blue. This means that there was a lot of very, very cold, 57-56F water NEARSHORE!
Comparing the Terrafin chart above of Monterey Bay for August 15th, we can see how the recent WNW winds impacted the SST from August 13th.
Now, let's look a little to the north at the Half Moon Bay, SST chart from August 17th.
Nearshore cool waters are smaller, while warmer water moved in closer to the 50 and 100 fathom lines.
Whoaa! What do we have here? Seriously cold water off Point Reyes, and Bodega Bay!
Sooty Shearwaters are streaming north, keeping up with the movements of the nearshore cool water bands. That's how it looks to me. To be sure, we still have loads of nearshore cool water in Monterey Bay and a few other places along the central coast. And, in two day's time, this will change again. The ocean is very dynamic, and hardly a homogeneous habitat, very unlike walking in a redwood forest — picture those redwood trees moving around every night and day!
Therefore, FOOD IS NOT EVENLY DISTRIBUTED AT SEA!
Sooty Shearwaters feed on schooling anchovies, below. We are primarily seeing these anchovy schools in COLD WATER! Last fall, a block of anchovies the size of Manhattan remained stationary in Monterey Bay for weeks, being gorged upon by not only Sooty Shearwaters, but some 100 HUMPBACK WHALES and large herds of hundreds of CALIFORNIA SEA LIONS.
Pretty much the same thing is happening this year, although only about 50 whales are feeding in Monterey Bay.
MASSES of ANCHOVIES in Monterey Bay this week.
Image by Tim Zoliniak, copyright.
Anchovies, and other species (mackerel and sardines) of "forage fish" are critical food for shearwaters, especially. Audubon California advocates to protect these stocks. The central coast anchovy population crashed in 2008. During the subsequent falls, Sooty Shearwaters were streaming along the coast, looking for schools of anchovies, but not finding them! In 2012, the anchovies returned!
Some folks are saying that 2015 might be a record-breaking year for anchovies in our area.
There is a fishery for anchovies — many are ground up into pellets that are fed to farm/captive-raised salmon. Please think about that the next time you eat salmon in a restaurant — and, ORDER ONLY WILD CAUGHT SALMON!
Two PINK-FOOTED SHEARWATERS, above.
Image, copyright, Beth Hamel.
Shearwater Journeys' six recent pelagic trips have detected massive numbers of SOOTY SHEARWATERS, primarily near shore, while offshore, PINK-FOOTED SHEARWATERS flocks are more numerous. This leads me to believe that the Pink-footed Shearwaters's preferred prey item is something that they are finding offshore. IT'S ALL ABOUT FOOD!
BULLER'S SHEARWATER, above.
Image, copyright, Beth Hamel.
Sightings of BULLER'S SHEARWATERS have been very few so far this season.
I believe the reason for this is that they tend to border the "hard edge" that tuna fishermen refer to where there is a distinct and abrupt change in SST from, say 59F to 61F. We have not been able to detect any "hard edges." Tuna fishermen (albacore) refer to the Buller's Shearwater as one of the "tuna birds," their association is so closely related to albacore. These shearwaters may feed on PACIFIC SAURY which is something that the albacore feed on as well. It's all about FOOD!
SCRIPPS'S MURRELET, above, Half Moon Bay, California.
Image, copyright, Will Brooks.
SCRIPPS'S, CRAVERI'S and GUADALUPE MURRELETS are also usually associated more often with "hard edges" and a SST of about 50-61F. However, they also like very clear, deep dark blue, almost black water, just like the albacore prefer. Pacific Saury are too big for them, but they may be feeding on the smaller prey that the saury feed upon!
To date, we have only found one SCRIPPS'S MURRELET, the one above.
But, that could change overnight, if we reach a "hard edge."
PIGEON GUILLEMOT with FLAT-BELLIED ROCKFISH which it was bringing to its young in the rock nest crevice at the jetty at Half Moon Bay, California.
Image, copyright, Beth Hamel
A BLUE WHALE blow shoots some 30 feet high.
Image, copyright, Beth Hamel.
Different species of seabirds are feasting on different marine prey, be it fish, or squid, or isopods.
We have not seen any krill, and it has been reported to be of very low productivity this year. Krill is the preferred prey item of the tiny CASSIN'S AUKLET and the world's largest animal, BLUE WHALE. We have only seen two BLUE WHALES, both at Monterey Bay on August 7th. These whales were traveling, not feeding. So, they were likely looking for krill. I predict that we will see Blue Whales on our Bodega Bay trip, September 18th.
Image, copyright, Beth Hamel.
The Farallon Islands where Cassin's Auklets breed, has been surrounded by cold water throughout the spring and now into summer. Although Cassin's Auklets, Rhinoceros Auklets, Common Murres, and Tufted Puffins did breed, it was not an off the charts breeding season. Cassin's Auklets did not double brood this year. They know there's an El Nino out there. Food for some of these species is limited.
Seabirds are well adapted to El Nino years.
They've dealt with it for eons.
But, the more recent man-made threats are something new for seabirds.
No other group of birds in the world is more threatened than seabirds.
And, that, my friends, is another blog post altogether!
Watching HUMPBACK WHALES.
Image, copyright, Will Brooks.
People travel many places around the world to observe striking wildlife spectacles —
Yellowstone, Serengeti, Svalbard, Antarctica —
yet one of the most amazing of these places is just offshore our coast!
HOPE TO SEE YOU OUT THERE!
LIVING THE SALT LIFE,
DEBI SHEARWATER
debi@shearwaterjourneys.com
TERRAFIN charts, used with permission.
Please do not reproduce.
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