(Endangered! is on view at the American Museum of Natural History, New York City, March 8 to September 2; an on-line version of the exhibit is available at the AMNH Web site.)

Visitors to the American Museum of Natural History's new exhibit, Endangered!, are greeted by starkly beautiful, black-and-white portraits of such "threatened" species as the spotted owl, the pitcher's thistle and the grizzly bear. Because Endangered! is, at its core, about the loss of life, there are naturally not many living things to be seen here, just images. Dioramas containing stuffed-and-mounted creatures awaken onlookers to the majesty of animals such as the mesmerizing Bengal tiger. Like photos of deceased family members that sit atop a mantle, they silently beckon viewers to acknowledge their physical absence. No matter how realistic and artistic these representations may be, however, they are still lifeless. In contrast is the lively Gator Hole, where the bellows of American alligators drown out the surrounding conversations. The diorama of an Everglades watering hole is teeming with life--from the river otter to the black-crowned night heron to the pig frog--a reminder that this ecosystem, while in jeopardy, remains vibrant.

The mood of Endangered! is twofold: the quiet, dimly lit areas induce visitors to ponder and lament what has already happened, whereas the lively and brighter spots help ignite hope for what may yet be done. The exhibit's most ominous expression of the threat of endangerment appears in the aptly named "Extinction Tomb." This semi-enclosed area has the unmistakable feel of a mausoleum. A large video monitor displays a time series of stills depicting the species that have become extinct, beginning in the year 1500. Just a handful of species vanished in the 1500s, as is the case with the next century and the one after. By the late 1800s, however, the tempo picks up: more and more pictures flash onto the screen.

Finally, we reach our current century. Specimens flicker by in an entrancing crescendo until the video becomes a frenzied slew of images. Viewers will be hard-pressed to recall which species have been lost: there were so many, and they disappeared so quickly. The Extinction Tomb is a powerful tool if visitors can bear the MTV-like pace of visual overload. The tomb contrasts pointedly with the nearby presentation of a timeline featuring dates of breakthrough conservation efforts and landmark works of biodiversity legislation, such as the Endangered Species Act.

Endangered! clearly documents the ways in which human alteration of the environment leads to endangerment. Loss of habitat, the effects of introduced species and overexploitation are all key threats. The potential consequences of species introduced into new areas is graphically showcased in a display sure to catch the eye of many spectators: a Volkswagen "Beetle" covered with zebra mussels. (Incidentally, Volkswagen is one of the sponsors of the exhibit.) The car was dropped into Lake Erie and left there for four months; the thick encrustation of zebra mussels demonstrates why this nonnative species has become such a pest and a threat to the local habitat. The display next to it offers a more unsettling view of the damage that a new predator might bring. The fierce Nile Perch, which ravaged the cichlid population in Lake Victoria, is startling in size and vividly makes the point.

Walking the fine line between educator and advocate poses a challenge for any curator organizing a project such as this one. Endangered! shies away from a detailed discussion of the issues behind the causes of endangerment--perhaps to avoid the perceived possibility of favoritism. Next to a portrait of a spotted owl, for instance, there is no indication of the recent conflicts between loggers and environmentalists. An unbiased exploration of differing agendas would provide more context, something that the more curious observers may be seeking. It is also ufortunate that the exhibit does not more clearly distinguish between a "threatened and an endangered species, nor does it describe how the status of animals can change. One redeeming quality, however, is that the AMNH links some of the Endangered! exhibits to displays in other areas of the museum.

Overall, the exhibit succeeds as a primer for the young and for others wishing a broad gloss on the issue of endangerment, although there is a rather disappointing paucity of child-oriented, hands-on activities. Videos that take viewers to distant places like China and an imaginary Meeps Island may pique fleeting interest. A "resource center" located at the end of the exhibit contains a hodgepodge of books for people of all ages to thumb through, but a class on a field trip would hardly receive the necessary guidance to fully use this facility.

The related Endangered! Web site largely repeats material from the "Guidebook" that accompanies the exhibit. Brief descriptions of endangered animals and habitats work seem appropriate to the Web format, as do the miniature essays on the ways that humans cause, and can prevent, biodiversity loss. A list of links offers a helpful starting point for further research--provided one has leisurely access to a computer hooked to the Internet. (Newcomers to the Web will also be put off by the design of the AMNH site, which opens outside links within a tiny frame; this shortcoming is easily overcome, but only for those who know to cut and paste URLs.)

It is evident that Endangered! is meant to be not so much interactive as proactive. Although the AMNH ostensibly tries to avoid politics, an exhibit like this one is inherently political. Curator Ross MacPhee coyly dances around the issue: "AMNH is not an advocacy group, but we advocate our own point of view." So the links on the Web site point to specific environmental sites, and the museum advises visitors, as they exit the exhibit, of five things they can do to help preserve biodiversity. The exhibit mentions learning about and thinking about the environment, along with respecting the planet's resources and using voting power to voice concerns. The last piece of advice: join an environmental organization.