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Collections & Archives


Specimens in the CAS / PNNM collection

Founded in 1857, the Chicago Academy of Sciences is one of America’s oldest scientific institutions.

Our scientific collections have been built since that time and have been used to help define human understanding of nature, ecology, and the diversity of life in the United States. The Academy’s collections include herpetology, mammalogy, ornithology, oology, entomology, malacology, paleontology, mineralogy, botany, photography and film, manuscripts and archives, and cultural artifacts.

You can explore some of our specimens and collections by checking out our Google Arts & Culture page or by searching Arctos.

Google Arts & Culture Page     Arctos

Jump To: About the Collection | Use & Access | Frequently Asked Questions

About the Collection

Specimens in a collection are like a physical snapshot in time, containing irreplaceable information. Often, the knowledge that can be obtained through careful study of these authentic artifacts was not anticipated when the specimen was collected. 

For example, a peregrine falcon collected in 1873 contains DNA, even though this molecule was unknown by scientists when the bird was put in our collections. Similarly, the eggs of this specimen might be compared with those of a more recent one to discover and quantify the effect of bioaccumulated toxins like DDT. In fact, egg shells from the 1800’s are thicker and have a stronger calcium and phosphorus matrix than do those collected in the 1960’s. As a result, peregrines became extirpated (locally extinct) in the eastern ¾ of the United States. Though the species has largely recovered (thanks to careful regulations, captive breeding, and reintroductions) the genetics of the population have changed. All of this is known because of specimens that were collected and preserved before the crisis occurred.

Through such natural history specimens, we have a physical, empirical record of the past. We can use these specimens to interpret our present place in history which then allows us to anticipate future conditions. This power to hold the past, understand the context of the present, and predict the future makes natural history collections an important and unique human resource.

Scientists and historians frequently access the collections while working on research projects. Nature Museum members and other groups also may have opportunities to take a special tour at the Collections Facility.

The museum collections have never been more accessible, thanks to grants from the Institute of Museum and Library Services (IMLS) and the Gaylord and Dorothy Donnelley Foundation. As of August 2012, every specimen in our collections was inventoried and digitally catalogued. Searches that used to take months now take minutes.

The number of specimens in each collection varies. Here is a “by the numbers” snapshot that just scratches the surface of the collections.

  • • 13,900 birds
    • 11,200 bird eggs and nests
    • 5,200 mammals
    • 23,200 amphibian and reptiles
    • 71,100 insects and spiders
    • 113,300 mollusks
    • 15,600 plants
  • • 500 linear feet of manuscripts and other paper records
    • 1,300 motion picture films
    • 2,300 cultural artifacts
    • 100,000 photographic images
    • 23,200 fossils
    • 11,100 geologic specimens

Use and Access

CAS/PNNM’s scientific collections and archives are stored at our off-site collections facility in the Ravenswood neighborhood. For research inquiries, please contact the Collections Department via email. Research visits to the collections facility are by appointment only. Information regarding use of and access to the collections may be found by clicking here. CAS/PNNM also has a non-lending library at the collections facility available for use on-site. The library catalogue is available through LibraryThing.

Our Education Department offers various programs for schools and teachers, such as Nature on the Go, that integrate specimens from the collections.

Frequently Asked Questions

What kind of information does the Academy have about its collections?

The data vary between different types of collections but a specimen should always include a data tag with the common and scientific name, where, when, and who collected the specimen, a description of the specimen’s habitat, and some basic measurements of the specimen such as weight in grams and length in millimeters. These data are used by a wide range of scientists from ecologists to taxonomists. Since we have so many specimens from more than a century ago, our collections are particularly valuable in showing change over time and predicting future trends.

How can we use this information?

There are many uses for specimen data including morphoplogical (attributes like size, shape, or color), chemical (attributes like DNA or isotopic signatures), and historical (attributes like distribution or population density). For example, a herpetologist may want to compare the present distribution of cricket frogs in Illinois with their historic distribution. Our collection database can supply the answers.  In this case, the data show that cricket frogs have disappeared from much of their former range. If the scientist then needs to use specimens from the early 1900’s to look for changes in chemical residue, bone structure or some other feature, our collection can supply them. Because we have the actual specimens, we can learn facts about the past that were not known at the time. By comparing this with current data we can then anticipate future trends.

Another use for natural history collections is morphometrics—the analysis of a species based on measurements of many specimens. These data, along with distribution data also gleaned from museum collections, form the basis of field guides. If you’ve ever gone bird watching or used a book to identify a plant, you’ve used data from a collection.

How can our collections help us understand the past?

The specimens in a natural history collection are like physical snapshots in time. They record data that cannot be reproduced. In many cases, questions that can be answered by the specimens were not anticipated when the specimens were collected. For example, all biological specimens contain DNA but, as far as scientists in the 1800’s knew, DNA did not exist. Yet, as an intrinsic part of the specimen, they collected and preserved that data along with the specimens they deposited and today that DNA can help us understand more about the past and the present.

What kinds of information are scientists seeking?

As our knowledge of the natural world grows and as we create new ways to gather information, the questions that can be answered by specimens increases. In the past, a scientist often used measurements of a specimen’s bones to distinguish one species from another. Such measurements are still important data points but today we can also use DNA from those same specimens to understand the evolutionary path that resulted in the two species in the first place. Since the specimen is a physical record from the past, it contains irreplaceable information that awaits the a creative scientist with the right tools. In the future, scientist will still be using old specimens to answer new questions.

Some examples of how Academy specimens have been used in different ways include: analysis of preserved stomach contents to learn about the diet of baby massasauga rattlesnakes; measurement of Ivory-Billed and Pileated woodpecker bills to determine the width of the chisel marks left in trees by large northern individuals and small southern individuals; and chemical extraction to quantify the stable isotope ratio in the fur of urban and rural squirrels as a way to show dietary changes across an urban/rural gradient and through time.

Aside from scientists, who else uses our collections?

Academy scientists have been collecting and preserving examples of local biodiversity for more than a century and a half. Most of these specimens have been made into study skins and are used for scientific analysis that is later published in the form of peer-reviewed papers and field guides. Most of your knowledge of nature has its roots in information first published by scientists using study skins.

Some specimens have been mounted in life-like poses for use in exhibits. This kind of taxidermy takes considerable skill, artistry, and time but results in a specimen that shows the beauty and drama of a living animal. Such specimens allow a visitor to see details that you could never observe on a living individual. For this reason, artists, commercial photographers, and movie companies have used our specimens.

Mounted specimens and study skins may also be loaned to other institutions to complete a study or augment an exhibit.

Specimen data, field notes, and photographs often accompany specimens. Such information is used widely by historians, authors, and scientists as they document the past, interpret the present, and imagine the future.

Contact the Collections Department at with additional questions or inquiries.

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