DeJong is measuring the duck eggs in several museum collections --
from the Smithsonian Institution, in this case, where Bendire was the
first 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.
"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 said. "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. They may not breed, but if they do
attempt to breed, they're not going to have as many nutrients available
to them to produce those eggs. Our hypothesis is that those eggs will be
smaller then."
The project is influenced by studies that SDSU Distinguished
Professor Carter Johnson and his colleagues have done by examining how
the future climate would affect water levels and waterfowl production in
the Prairie Pothole Region, a region in South Dakota and neighboring
states and provinces that produces more than half of North America's
migratory ducks. Johnson's data from the start of the 20th century until
now suggest that some western parts of the Prairie Pothole Region are
becoming hotter and drier. If the trend continues, ducks may produce
fewer young if drought forces them to nest in unfavorable locations
elsewhere.
DeJong's adviser, Professor Emeritus Ken Higgins of SDSU's Department
of Wildlife and Fisheries Sciences, came up with the idea of
investigating whether ducks have already been adjusting to such changes.
And he came up with the ideal mechanism for the study -- assembling
data from decades of egg collections in natural history museums.
"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 over the past 40 to 50 years. However, that data
by itself says nothing about why. Searching for the main causes of the
size changes in duck eggs will be the next stage of research for the
project.
DeJong will 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 for much of her data.
"These early bird egg collectors, largely known as 'oologists,' were
kind of 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 said.
The museum duck egg collections she has visited to gather data
include those at the University of Kansas; the University of Nebraska;
the University of Minnesota in St. Paul; the University of Wisconsin in
Green Bay; the University of Michigan; Michigan State University; the
Western Foundation of Vertebrate Zoology in Camarillo, Calif.; the
Smithsonian Museum of Natural History in Washington, D.C.; the American
Museum of Natural History in New York; the Oakes Museum at Messiah
College in Grantham, Penn.; the Field Museum and Chicago Academy of
Sciences in Chicago, Ill.; and the Royal Ontario and Royal Alberta
museums in Canada.
Counting current and recent data provided to her by other researchers
who are interested in the project, DeJong expects to include data from
about 60,000 eggs by the time the study wraps up in 2012. For example, a
cooperating researcher has shared data on 30,000 eggs from Alaska
alone, but other cooperators have shared data from as far afield as Nova
Scotia. The U.S. Fish and Wildlife Service is funding most of the cost
of the research.
Regardless of what she finds, DeJong said the study also will provide
baseline data for scientists -- a source for comparison of future
research.
"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. None of this type of research would have been possible
without the actual presence of the eggs because the metrics needed for
this project could not have been obtained solely from photo image alone.
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."