Tuesday, September 20, 2016

Jaegers in the Rips

Tis the season when all three species of regularly-occurring Jaegers (Skuas for our friends across the Atlantic) vacate their breeding grounds on the Arctic tundra and flood down both coasts to spend their non-breeding life out at sea. Here in Cape May our most common jaeger seen from land is the Parasitic Jaeger (Pomarine are more often far offshore, and Long-tailed are simply rarer, but regularly encountered on offshore pelagic trips in small numbers).

While individual Parasitic Jaegers can be seen year-round here (which include some non-breeding birds that spend the summer offshore), fall is one of the best times to see numbers of these pirates of the high seas including their wide range of variation in age and color morph. One of the best areas to view these birds is in the Cape May "Rips", the tumultuous upwelling caused by rising and falling tides streaming over and around underwater topography at the mouth of the Delaware Bay. These upwellings bring nutrients to the surface, which increase food availability from the tiniest zooplankton to the largest marine mammals. In the middle of this faunal continuum, of course, are the birds; dominated by gulls and terns.

Three adult light-morph Parasitic Jaegers harassing a Laughing Gull
© David La Puma
Cape May "Rips", October 2015.
Parasitic Jaegers get their name from their tendancy for hunting down gulls and terns and chasing them until they regurgitate their last meal, then swooping down and gobbling it up themselves. Kleptoparasitism, literally parasitism by theft, is the term used to describe this behavior. Knowing this behavior can actually help you determine whether you're looking at a jaeger in the melee of feeding gulls and terns.
A more "typical" view from shore, a distant immature dark-morph
Parasitic Jaeger circling back on a laughing gull. © Clay Taylor
Cape May "Rips", September 2016.
Now is a good time to keep track of the local tides, and get out to one of several locations around Cape May Point where viewing the rips is best. The Coral Avenue and St. Mary's dune crossovers can be excellent, as can the dune crossover at Brainard Ave. Our 2016 Hawkwatch Counter, Erik Bruhnke, has also been seeing them right from the hawkwatch platform at Cape May Point State Park! The best time to maximize your chances of seeing multiple jaegers is during the three hours before low tide, as the Delaware Bay empties into the Atlantic Ocean, bringing many nutrients with the outgoing water. The second best time is on the rising tide, again, beginning about three hours prior to high tide. Of course the magnitude of the rips behavior is dictated also by the amount of tidal fluctuation, so tides closer to new and full moons are going to produce more upwelling activity, which means that right now is a great time to scan the rips for jaegers! (the full moon was only a few days ago). As of yesterday there were up to six Parasitic Jaegers visible during the hours prior to low tide. How many will there be today? You'll have to go and find out!

A lone Common Eider was also present near shore on the east side of the
St. Peter's Jetty © David La Puma

Swarovski Optik Nature (North America)'s Naturalist Market Manager,
Clay Taylor, digiscopes jaegers a mile away through his Swarovski ATX
spotting scope. © David La Puma

Gulls are a stumbling block for many new to birding...
but when they pose together nicely like this, they're downright easy!
L->R: Herring Gull, two Great Black-backed Gulls, and Lesser Black-backed Gull
© David La Puma

For more information please feel free to stop by NJ Audubon's Cape May Bird Observatory, at 701 E Lake Drive, Cape May Point, 08212. We're open and here for you daily from 9:30am - 4:30pm.

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