The Cape is currently under siege by pirates – over a thousand have been seen in the last week alone. Robberies at sea have skyrocketed, and you can see the high-speed chases for yourself at places like Race Point in Provincetown.
But you needn’t worry too much unless you happen to be a Common Tern, because these buccaneers are birds, and they’re only out to steal baitfish from honest, hardworking seabirds. They’re known as “jaegers”, and three species terrorize our waters each late summer and fall – one large, one medium, and one small.
Pomarine Jaegers are the big bruisers of the family, and are usually scarce within sight of land. They typically chase down bigger birds like gulls and larger shearwaters. Parasitic Jaegers are medium sized, relatively common, and well–named. This is the default species in this area - a couple of Parasitic Jaegers working over a flock of terns is a classic late-summer scene on Cape Cod, which is one of the best and only places in the world to see this phenomenon so easily. The rarest of the trio is the relatively slim Long-tailed Jaeger. Previously considered exceptionally rare in Massachusetts, the exponential rise in digital photography has shown us otherwise; we were almost certainly overlooking them in the past. Since the three species overlap in size and display a bewildering array of immature plumages and color morphs, jaeger identification is fraught with peril, even for the most experienced birders armed with the finest cameras.
But on the summer Arctic tundra, jaegers are striking and distinctive in their breeding finery, sporting long central tail streamers and black caps that cover the eyes, an appropriate look given their penchant for banditry. Jaeger is the German word for hunter, which is mildly ironic for birds who spend more than half their life stealing food from other birds. But in summer when they are raising their young, they make a more honest living hunting lemmings or birds. A single family of Pomarine Jaegers can eat over 1000 lemmings in a summer, making them the most important predator of lemmings in many Arctic regions. But once the chicks have been raised and it’s time to migrate, jaegers turn to piracy once again, spreading throughout the southern oceans to harass a wide variety of the world’s seabirds.
As you’ve no doubt gathered, birders like me go wild for jaegers. But the uninitiated may wonder what the fuss is about, because with the distant views they typically allow, nonbreeding jaegers basically look like gulls, albeit with a bit of a funny tail. But to see a Parasitic Jaeger shift into fifth gear in pursuit of another seabird, matching every hairpin turn in breakneck, beak-to-tail pursuit, is to see one of the bird world’s greatest athletes in action. Even in leisurely flight, the power and speed of a jaegers is evident in every wingbeat compared with a gull. Many liken them to falcons of the sea, and, like falcons, some jaegers will pursue and kill smaller seabirds, often forcing them into the water from above. Birders are willing to overlook this anti-social behavior in exchange for the thrill of seeing them in action.
We have a lot of opportunities to see jaegers here on the Cape, including whale watches, some of the smaller pelagic birding trips going out of Chatham and Provincetown, and just watching from land at both bayside and outer beaches. But in the coming weeks our thousands of staging terns will head south, taking the jaegers’ easy meals with them, and they, too will be gone, thus completing yet another cycle in the Cape’s annual ornithological rhythms.
