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Work of 19th-century oologists enables researcher to track climate change with duck eggs

BROOKINGS, S.D. — Julie DeJong can’t set foot on the ground of an Oregon marsh to gather duck eggs on a spring day in 1875.

Julie DeJong

South Dakota State University researcher Julie DeJong measures duck eggs in university and museum collections for clues about how duck species may have responded to climate patterns and long-term climate change.

But Charles Bendire did. And thanks to a research project that is the next best thing to time travel, DeJong is measuring the duck eggs in a number of museum collections, such as those at the Smithsonian’s National Museum of Natural History in Washington, D.C.  Bendire (1836-1897), an ornithologist and the Smithsonian’s first honorary curator of the discipline known as oology, or the study of birds’ eggs. When her project is done, DeJong will have assembled and analyzed a metrics database on perhaps 60,000 duck eggs representing at least 40 species and subspecies of ducks found in North America.

What she learns could ultimately add new knowledge about how waterfowl respond to climate cycles and long-term climate change.

DeJong is a Ph.D. student in South Dakota State University’s Department of Wildlife and Fisheries Sciences. Part of her work involves logging current measurements of duck eggs that cooperating researchers are gathering for her in the field, as well as recent measurements from studies in the past few years. But DeJong is also visiting museums across the U.S. and Canada to measure duck eggs collected by naturalists up to 150 years ago to build a database of how the dimensions of eggs have changed, if they have changed, over past decades.

Charles Bendire

Charles Bendire, an ornithologist who donated many eggs to the Smithsonian.

“What we’re trying to do with this project is to see, through different drought cycles and heavily wet cycles, if the size of the eggs from these ducks will change,” DeJong says. “The reason that they might change in size is due to changes in the nutrient levels from foods such as invertebrates that are available during breeding. If, say, the Prairie Pothole Region is completely dried up due to drought for several years in a row, those ducks are going to experience a drop in the nutrients they’re used to getting…. Our hypothesis is that their eggs will be smaller then.”

“It is like time travel, because there’s no way I could go back 150 years and collect that kind of data,” DeJong said. “There is so much information sitting there in these museums that people forget about. When people these days plan a research project, they’re starting today and going into the future. They don’t usually have the opportunity to look backward.”

Looking backward is already revealing some surprises. While it’s too soon to draw firm conclusions, DeJong noted that her preliminary data does suggest that a few species, such as the Lesser Scaup, appear to be producing smaller eggs during the last 40 to 50 years.

DeJong plans to plot the coordinates of the egg collections on a map of North America using geographic information system technology, and she’ll overlay that map with new layers of information about ecological region and climate patterns through the years. Ultimately she’ll be able to determine whether changes in duck egg size appear for specific species or ecological regions or time periods.

Since duck egg collectors weren’t spread out systematically over time or geography, there are gaps that pose challenges for statistical analysis. One way DeJong tries to deal with that is by simply visiting more museums and mapping the data from more eggs. She’s indebted to 19th century naturalists—the Smithsonian’s Bendire and others like him—for much of her data.

“These early bird egg collectors, largely known as ‘oologists,’ were a breed all their own. They went out and trekked into swamps, prairies and woodlands all over the United States and Canada and the far reaches of Alaska and collected these eggs, some of them just for their own enjoyment, some for commercial sale, and some of them to document what was there,” DeJong says.

“Early oologists were the first birders in North America, yet most of them were not scientists per se, but an assortment of doctors, farmers, hunters, and nature enthusiasts. Our early information on the breeding season, habitat use, and physical descriptions of the breeding adults and their nests and eggs of hundreds of North American birds came from oologists,” DeJong said. “By collecting the eggs and other collateral data, they were not only collecting beautiful objects to put in a cabinet drawer, they were also documenting the natural history and breeding history of the birds, which can be used by scientists today and in the future. I hope my research stimulates thought about the possible uses of these egg collections and of other kinds of specimen collections in museums around the world. By making use of these collections, we pay tribute to these naturalists for their hard work, perseverance and love of nature.

–Source: South Dakota State University


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