Pomarine Skua/Pomarine Jaeger Stercorarius pomarinus, Nanhui, Shanghai, 20 Oct. 2016.

The Shanghai Skua

by Craig Brelsford
Founder, shanghaibirding.com

Found at Cape Nanhui on Wed. 19 Oct. 2016: Pomarine Skua (called Pomarine Jaeger in North America). This first record for Shanghai was discovered by local birder Hé Xīn (何鑫) in the defunct nature reserve 1.4 km inland from the East China Sea. Kai Pflug was also on hand. Hé Xīn and Kai spread the news through our Shanghai Birding WeChat group, and the next day Elaine Du and I found the skua at the same spot (30.921625, 121.958940). The skua stayed four days, until Sat. 22 Oct.

The seabird appeared healthy, alternately feeding, preening, and roosting. Its plumage was shiny, and I saw no evidence of injury. It was a healthy refugee blown west by Typhoon Haima.

Pomarine Skua/Pomarine Jaeger
Look into the eyes of a predator. For many a lemming on the Arctic breeding grounds, this cold stare is the last sight they will ever see. National Geographic calls Pomarine Skua a ‘bulky brute with a commanding presence … a Rottweiler among the jaegers.’ (Craig Brelsford)

As sightings of skuas on the Chinese coast are rare, and because skuas have a bewildering array of plumages, at first there was some confusion about the species of our bird. It soon became clear that the vagrant was either Pomarine Skua Stercorarius pomarinus or Arctic Skua (IOC: Parasitic Jaeger) S. parasiticus. But which?

POMARINE ID BASICS

To answer that question, we needed photos, and so on Thurs. 20 Oct. Elaine and I drove to Cape Nanhui, the coastal birding site in Pudong.

We quickly found and photographed the bird. After examining our images, talking to other birders, and studying the books, we determined that it is a pale-morph adult pomarinus in non-breeding plumage. Here’s why:

— S. pomarinus is larger and bulkier than the other jaegers (small skuas), in particular the jaeger that it most resembles, S. parasiticus. The jaeger we found was large and bulky.

Pomarine Skua/Pomarine Jaeger
Pomarine Skua Stercorarius pomarinus. This heavy-set jaeger appears bulkier before the legs than behind. Note its bull neck, barrel chest, and short tail. Size is about equal to Black-tailed Gull Larus crassirostris (Brazil). S. parasiticus is equally bulky before and behind the legs, is longer-necked and less pot-bellied, and has a longer tail. (Craig Brelsford)

National Geographic describes pomarinus as a “bulky brute with a commanding presence [and a] thick bull-neck—a Rottweiler among the jaegers.” S. pomarinus, Geographic adds, “is the bulkiest [jaeger] and appears pot-bellied and very deep at the chest. … Often it appears there is more body before the wing than behind the wing.”

The image above is in line with that description. Below, another image illustrating the bulky shape and barrel chest.

Pomarine Skua/Pomarine Jaeger
The skua family (Stercorariidae) is monogeneric; all seven species are in the genus Stercorarius. In the United States and Canada, the smallest three Stercorarius are called jaegers, a convention followed by the IOC. The largest of the jaegers is Pomarine, the next-largest is Arctic Skua/Parasitic Jaeger, and the smallest is Long-tailed Skua/Long-tailed Jaeger S. longicaudus. All three jaegers breed on Arctic tundra in Eurasia and North America and winter at sea. All are kleptoparasitic—they steal food from other birds. This habit gives rise to the Chinese name for the family: ‘thief-gull’ (贼鸥). (Craig Brelsford)

In adult pale-morph pomarinus, the black helmet reaches below the gape, and black plumage surrounds the base of the bill. Most pale-morph parasiticus show a white spot at the base of the upper mandible and a less-extensive helmet that does not reach below the gape.

Pomarine Skua/Pomarine Jaeger Stercorarius pomarinus, Nanhui, Shanghai, 20 Oct. 2016.
The Shanghai pomarinus is a pale-morph adult in non-breeding plumage. (Traces of the yellow breeding plumage can be seen here on the cheeks and throat.) Its helmet reaches below the gape, and it lacks a pale spot at the base of the upper mandible. (Craig Brelsford)

Below, another close-up of the head. Note here and above that, unusually for pomarinus, the bill appears almost all-black.

Pomarine Skua/Pomarine Jaeger
The Shanghai pomarinus has an unusually dark bill. (Craig Brelsford)

Adult pale-morph pomarinus is more heavily barred than parasiticus. Most adult pale-morph pomarinus show a coarse breast band and dark barring on the flanks. Most adult pale-morph parasiticus show a diffuse greyish-brown breast band and lack barring on the flanks.

skua-pomarine008
Our pomarinus shows broad, coarse barring across the breast and on the flanks. (Craig Brelsford)

There are several other ID points, some of them, such as tail streamers, not visible in The Shanghai Skua. The points discussed above, however, are enough, we think, to clinch the ID.

OTHER PHOTOS

Enjoy these other photos of the rarity.

Pomarine Skua/Pomarine Jaeger
When Elaine and I arrived Thursday morning, a Grey Heron was harassing the strange intruder. (Craig Brelsford)

The skua was very tame and performed various functions in its unaccustomed surroundings. It scratched itself (below), bathed, scavenged dead fish, and occasionally took short flights.

Pomarine Skua/Pomarine Jaeger Stercorarius pomarinus, Nanhui, Shanghai, 20 Oct. 2016.
(Craig Brelsford)

Its most common activity was roosting on the mud bank.

Pomarine Skua/Pomarine Jaeger
(Craig Brelsford)

Kai Pflug got the photo below of the skua with wings upraised. Note the unbarred underwing and pale flash at the base of the primaries, further evidence that the skua is an adult.

Pomarine Skua/Pomarine Jaeger
Photo taken 19 Oct. 2016 by Kai Pflug.
Pomarine Skua
Compare the images of our non-breeding Pomarine with this shot of an individual in breeding plumage. Alaska, June. (Daniel Pettersson)

Hé Xīn (below) found The Shanghai Skua on Wed. 19 Oct. 2016, a historic first record for Shanghai. The next day I met Hé Xīn at the site.

Craig Brelsford (L), Hé Xīn (何鑫)
shanghaibirding.com editor Craig Brelsford (L) and Shanghai Skua discoverer Hé Xīn (何鑫), Cape Nanhui, 20 Oct. (Elaine Du)

BIBLIOGRAPHY

Note: Nearly every major field guide covers skuas, a cosmopolitan family. This is a partial list showing the main works I consulted as I researched Stercorariidae.

Alderfer, Jonathan, ed. National Geographic Complete Birds of North America. National Geographic Society, 2006. Section “Skuas, Gulls, Terns, and Skimmers” by N.G. Howell and Alvaro Jaramillo. Jaegers, pp. 237-9.

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Brelsford, Craig, moderator. Shanghai Birding, a WeChat chat group. News about the sighting of Pomarine Skua was disseminated by Hé Xīn and Kai Pflug through this chat group.

Brazil, Mark. Birds of East Asia. Princeton University Press, 2009. Skuas, pp. 230-3.

Grimmet, Richard & Carol Inskipp & Tim Inskipp. Birds of the Indian Subcontinent. Christopher Helm, 2011. Pomarine Skua and Arctic Skua, p. 182.

Peterson, Roger Tory & Virginia Marie Peterson. Birds of Eastern and Central North America, 5th ed. Houghton Mifflin, 2002. Jaegers, p. 168.

Svensson, Lars & Killian Mullarney & Dan Zetterström. Collins Bird Guide, 2nd ed. HarperCollins, 1999-2009. Skuas, pp. 174-7.
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Craig Brelsford

Craig Brelsford is the founder of shanghaibirding.com. Brelsford lived in Shanghai from 2007 to 2018. Now back home in Florida, Brelsford maintains close ties to the Shanghai birding community and continues his enthusiastic development of this website. When Brelsford departed China, he was the top-ranked eBirder in that country, having noted more than 930 species. Brelsford was also the top-ranked eBirder in Shanghai, with more than 320 species, as well as Shanghai’s Cape Nanhui, one of the best-known birding spots in China. Brelsford coined the term “Cape Nanhui” and continues to advocate for the conservation of the most southeasterly point in Shanghai. Brelsford's photos of birds have won various awards and been published in books and periodicals and on websites all over the world. Brelsford is a graduate of the University of Florida and earned a master's in business administration at the University of Liege, Belgium.

2 thoughts on “The Shanghai Skua”

  1. From Kai Pflug’s photo it looks as if the skua was in the early stages of primary moult but because the two wings are superimposed it’s a bit difficult to work out the details. Are there any other “open wing” photos?

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