Cape Cod Sea Birds

Seabirds in June 2012

The previous blog showed a few of the whale images taken June 10th about 25 miles east of Chatham Light off the coast of Massachusetts. There were about 80 whales and thousands of shearwaters attending to a profusion of Sand Lance. The whales were mostly humpbacks although a few Minke skittered in and out as well. The whales were feeding inside bubble clouds and were seen in groups up to six individuals as part of the many bubble-teams. Most associations were of fewer whales and one individual kick-fed without joining the bubble gangs during the four hours we were with them.

One of the many marvels of this scene were the attending sea birds. Estimates of Sooty Shearwaters exceeded 3000 and there were Great and Manx Shearwaters as well. In the feeding mix were a couple Pomarine Jaegers and we saw two Parasitic Jaegers as we traveled to and from the feeding area. The bird surprise for the day was (perhaps) two fold; Wilson’s Storm-Petrels were nearly absent and we had two Razorbills on the way around Race Point (Provincetown) heading home to Plymouth.

Great Shearwaters are usually very common in Gulf of Maine and coastal Massachusetts waters – and I am sure they will be more common as we move through the summer months. However, there are only a handful out there right now. The water is green with phytoplankton and there are tons of Sand Lance; the small forage fish that is the basis of Massachusetts fisheries (and whaleries and sea birderies as well – I know those aren’t real words but they imply the importance of these small fishes).
Great Shearwaters have a wingspan of about 44 inches and they rarely weigh two pounds; 30 ounces is about average. They nest at the edge of the Southern Ocean; mainly on the islands of Nightingale, Inaccessible, Tristan de Cunha, and Gough. Adult birds start a long migration north in April and molt worn feathers in the waters off New England and the Canadian Maritimes in July, August, and September. They return to the very far south; often via Greenland, Ireland, and the western European coast, in September and October and lay eggs deep in the Southern Hemisphere in November. 
Great Shearwaters are strong and direct flyers. They bound and shear through heavy weather with ease. They eat small fish and squid from the surface and just below the surface though they are capable of deeper fishing forays. Here in Massachusetts they are associated with Sand Lance and often with groups of feeding whales – as we saw this past Sunday.

There were only about 30-35 Great Shearwaters and about the same number of Wilson’s Storm-Petrels out there ; however there were thousands of Sooty Shearwaters. I put 3000 as my number (in eBird) but some observers went a bit higher and some a bit lower. The Sooty Shearwater (below five images) is uniformly dark except the underwing is often silvery/shiny, the tail is dark brown and the underside is usually a bit lighter. 
The wing span of an average Sooty is 40 inches and the body length is about 17 inches. They weigh (on average) 28 ounces or about a pound and three-quarters. This varies by sex, season, feeding habits, and location on the migratory route. There is little to eat in the middle latitudes of the planet so they are probably thrilled to see the Sand Lance after crossing the Tropics and the Equator.
As a species the Sooty Shearwater is an abundant seabird. There are huge numbers in the Pacific and the Atlantic (and smaller numbers in the Indian) Oceans after their breeding season deep in the Southern Hemisphere. They can migrate past a point of land along the California coast (say Monterey) in the tens of thousands a day. They nest widely around the Southern Ocean. Large numbers on the New Zealand islands well to the south of Stewart Island (like and smaller populations off the tip of South America on both the Argentine and Chilean sides.

Sooty Shearwaters are one of the species that has been called “mutton bird”. In New Zealand the Maori people still harvest young shearwaters, pluck them, and then salt them. They are stored in a bucket and keep about a year. The birds harvested this way are youngsters about fledging age. There are stories that say they taste like fish and others that say they taste like mutton – I have never tried it. 
The picture below was taken in a butcher shop in New Zealand in 2012. The proprietor showed me a stored-in-brine muttonbird waiting for a buyer.

There are still millions of Sooty Shearwaters around the world, but because the overall population numbers have been declining quite rapidly there is great concern about the health of the species and the health of the oceans. The bird, like almost all pelagic species, is on a watch list.

The number of whales and seabirds was very large and the adrenaline flowed freely. But we had to travel a great distance to find this group of birds; they were not widespread and not in many of their usual haunts. This was an exciting day most certainly but every day with sea birds is both exciting and tinged with despair. Forage fish are being harvested in huge nets; 20 and more tons of small fish are scooped up in a single haul. The harvest is un monitored at this point and the turtles, mammals, and other by-catch is not reported and certainly not understood. Sardines, anchovies, capelin, sand lance, herring, mackerel, and  other “forage” fishes are often ignored by fisheries managers and this will eventually have disastrous results.
There will be at least one more blog entry for this outing — jaegers and an overview will follow shortly. 

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