Published: February 8, 2016

Of Ivory Gulls and Parasites

Ivory Gull (Pagophila eburnea) photo by Nathan Goldberg.

On the morning of January 7, I received a phone call from our former intern Nathan Goldberg, currently a student at Cornell University, who was birding in northeast Minnesota. "I just found a roadkill Spruce Grouse, do you guys want it?" That was an easy question: "Of course we do," I replied. Spruce Grouse is a bird of the North Woods, far from Chicago, so this was an excellent opportunity to get a fresh specimen of a species that rarely comes into the collection. Plus we have all of the necessary permits to receive specimens from Minnesota.

That was just the beginning of the story. One of the main reasons Nathan was in that area, along with dozens of other birders, was to see the rare Ivory Gull that showed up a week earlier on the Duluth lakefront and was being seen daily.

Not long after his phone call, I saw a distressing message on Facebook--an Ivory Gull had been found dead, mostly eaten by a mammal, just across the border in Wisconsin. Only the head and wings remained. Laura Erickson, a birder who lives in Duluth, went out and salvaged what was left of the specimen after learning of the bird's demise. As is the norm these days, all of this was known in real-time thanks to social media.  Nathan then contacted Laura to ask if, while he was at it, he could take the Ivory Gull remains to the Field Museum along with the Spruce Grouse that was already in his trunk. She agreed. In the meantime, a living, breathing Ivory Gull was seen again in Duluth! (I highly recommend reading Laura’s account of the remarkable situation). Late the following night, Nathan, knowing that his mother wouldn't approve of a big bag of dead birds in her freezer, stopped by my apartment on his way home from Minnesota to drop off the specimens.

As an intern at the Museum, Nathan had worked with Jason Weckstein, a former staff scientist whose research focuses on birds and their associated parasites. Not wanting to miss an opportunity for further study, Nathan asked that we wait a week to prepare the specimens so he could come in to the museum and examine them himself for lice. That wasn't a problem, and we both knew Jason would be thrilled to receive anything that he found. 

The following week Nathan came to the museum to do just this. We had pulled the birds out of one of the Bird Collection’s many freezers that morning, so they were thawed and ready to be "ruffled," the term for rummaging through a bird’s plumage to collect its ectoparasites: lice, mites, fleas, and ticks in particular. We find ectos, as we call them, on roughly 50% of the birds we check; today, however, the success rate was 100%. Nathan found lice on both the Ivory Gull and the Spruce Grouse as well as a mite on the gull. It's entirely possible that some of the parasites represent new species. We checked the “Bird Louse Bible,” and it turns out that several louse species have been found on Ivory Gulls—the first was described way back in 1780! Just one species is known from Spruce Grouse.

Tom Gnoske, our Assistant Collections Manager, then prepared both birds as specimens. The Ivory Gull specimen consists of one wing, the head feathering, the skull, plus additional feathers. The Spruce Grouse was prepared as a study skin, with a partial skeleton saved as well. As we do for every specimen that comes through the prep lab, tissue samples were saved from both birds to preserve their DNA. A quick search of VertNet, the online database of museum bird collections, shows that the Ivory Gull tissue sample may be only the second one in a museum collection. 

Ivory Gull is a rare bird, making this a unique opportunity to study its parasite fauna and collect a tissue sample that can be used for genetic studies in the future. It is classified as Near-threatened by BirdLife International because it “has declined rapidly in part of its range,” indeed by as much as 80% in Canada over the last thirty years. Part of the problem may be mercury poisoning, which increased in their systems by 45 times in 130 years. Whether or not this is related to birds showing up so far out of range is yet to be studied. But thanks to the quick work of birders and the wonders of social media, when it is studied there is no doubt that this specimen will be used.