For the Birds Radio Program: Jaegers
This weekend I got the first lifer I’ve added in Wisconsin in well over a decade, when Russ and I spent a couple of hours at Wisconsin Point in Superior. In recent autumns, more and more birders have been gathering at the first parking lot at Wisconsin Point every day to watch for unusual gulls and jaegers. Gull numbers off Wisconsin Point seem to be highest on days when the landfill is open, and since jaegers harass gulls to steal their food, they are most likely to appear when gulls are abundant.
On Saturday, before Russ and I got there, all three jaeger species had been seen, but the Pomarine Jaeger had apparently gone elsewhere. The Pomarine Jaeger is the biggest and the rarest of the three jaeger species on their Arctic breeding grounds. This jaeger nests in the low-lying wet tundra near arctic coasts, and its breeding is strictly tied to lemming populations. Outside of the breeding season, Pomarine Jaegers spend their lives far from land, in tropical and subtropical oceans, eating some small seabirds, scavenging on whatever they can find, and stealing food from seabirds.
The smaller two jaegers are acrobatic and aggressive in stealing food from other birds—the Parasitic Jaeger even takes its name from this kleptoparasitism. The big Pomarine Jaeger isn’t as graceful in getting its meals—researchers studying it say it’s more likely to rely on surprise and brute force to attack birds feeding in the water rather than wing its way with graceful aerial maneuvers. I’ve only seen one Pomarine Jaeger in my life, on September 6, 1982, when one flew directly above me at Park Point.
The following May I saw a Parasitic Jaeger on Park Point. Parasitics are the primary predator of birds and eggs on the tundra. They also feed on lemmings, but have enough other food sources that their reproduction doesn’t depend on lemmings as it does for Pomerines. Those that nest near seabird colonies in the northeastern Atlantic and the Aleutians specialize on a unique form of kleptoparasitism—they force gulls and seabirds to disgorge their food and then deftly retrieve it in mid-air. They’re so good at this that of the three jaegers, the Parasitic is the one that hugs shorelines, so is the one most often seen along the Great Lakes. Russ and I saw two of them a few times on Saturday. They were partly hanging out together, flying or alighting on the water together, and they were also divebombing gulls, bringing them fairly close in for photographs.
The tiniest jaeger, the Long-tailed, is the most abundant and widespread of the three on the breeding grounds. Away from the tundra, this little jaeger tends to stay well out over the open ocean, so is the least often encountered on the Great Lakes. There have been a handful of sightings of Long-tailed Jaegers on our end of Lake Superior during the 3 decades I’ve lived in Duluth, but I was never in the right place at the right time till Saturday. The one we had was divebombing Ring-billed Gulls, which were much larger. My photos aren’t very high quality because the bird stayed pretty far out, but they show some dramatic interactions and anyway, I’m just thrilled to have any photos at all of this lifer. Kim Eckert sent a note on the MOU listserv reminding people that on October 15, 1980, exactly 30 years ago, all three jaegers were seen on Park Point. Apparently the Ides of October is the right day to get out there looking for jaegers, so I’ve already marked it in my calendar for next year.