Emperor penguins are very rare in captivity today, and the thought of keeping them alive in a zoo would have been considered ridiculous a century ago. These birds, however, preserved and displayed at the Field Museum, have been greeting guests for decades.
As a side note, zoo animals no longer seem as well suited for museum display as they once were. It does still happen, especially with very rare specimens (Cincinnati Zoo donated the body of a Sumatran rhinoceros to a museum for display), but museums may have become a victim of zoos' success. Many zoo animals live to be quite elderly these days, and might be less suitable for exhibition. A jaguar that I worked with passed away a year or so ago. I'm sure she was a beauty in her youth, but by the end her coat was shabby, she had scars (some from surgeries, some from fights), and she was missing part of an ear. No self-respecting museum would have touched her, as much as I adored her.
Taxidermy, it seems, has fallen by the wayside in public estimation. Many people associate it closely with its necessary act - the killing of an animal - and therefore with trophy hunting. Fair enough - many specimens, especially from the last century, were collected and donated by sportsmen. Theodore Roosevelt filled many a museum hall with his post-presidency safari in East Africa, blazing away at all sorts of now-endangered wildlife with the word "Bully!" on his lips. Besides, the argument goes, now we have other ways of learning about wildlife, like the Internet, and television, and zoos and aquariums.
That being said, there are still tremendous advantages to taxidermy and stuffed specimens. For one, a specimen will, if properly taken care of, last forever... or at least a very long time (many of the mammals I saw in the Field Museum were collected by Carl Akeley a century ago). Stuffed specimens don't require much space - you can fit all of the world's cats in less room that you would need to exhibit a (live) pride of lions, nor do they eat or... do the opposite of eating. A much smaller staff can curate an enormous collection. Also, you can get much closer to them for comparison and study. Furthermore, taxidermy mounts can enable us to study species which don't do well in captivity or otherwise aren't maintained by zoos and aquariums.
Lastly, for some species, such as the extinct birds I mentioned early, taxidermy is all that we have left of them. Unless cloning picks up, I'll never see a Tasmanian tiger or a Carolina parakeet, but I've seen several in museum collections. In the future, the same may be said about California condors or Sumatran rhinos. The last known specimens of some endangered amphibians or invertebrates are even now floating in jars of preservatives. In this way, natural history museums truly are the archivists of extinction.
Despite all of these advantages, I'll never feel the same way about a stuffed specimen as a real animal. Even when masterfully posed in a beautiful diorama, they never seem... real to me. When Carl Akeley first unveiled his masterpieces at the Field Museum (and later the American Museum of Natural History in New York, a quick stroll from the Central Park Zoo), people were awestruck. It seemed to them like the animals were frozen by a magic spell, and would start moving any second now. To be fair, the zoos of that age were very different from today, and nowhere near as proficient as displaying their animals... or keeping many of them alive for any period of time. That's probably why the mounts that impress me the most are those of animals that I've never seen in the flesh.
I think there is definitely a role for stuffed specimens (I have to keep catching myself so I don't type "stuffed animals" and conjure up Teddy bears) in education. I could certainly see them existing side-by-side with live zoo and aquarium animals. They could be used to highlight differences between animals, or to represent animals which can't be maintained in the collection (in the case of some marine species, like giant squid, fiberglass models would fill that same role). I know of at least two zoos that has a natural history museum on its campus, and more than one museum that has a small collection of living animals.
The Mexican subspecies of brown bear is now believed to be extinct. If we are ever to learn more about it, it will have to be using what little remains - such as these stuffed specimens.
After my morning at the Field Museum, I continued by stroll by Lake Michigan and visited the Shedd Aquarium. The museum collections were fascinating, in some cases hauntingly beautiful. But I was ready to spend some time among the living.
And, just for comic relief (not everyone is Carl Akeley), enjoy 20 taxidermists who seriously need their licenses revoked... like NOW!