Faced with a growing number of species headed toward extinction, some scientists and governments are seeking a better way to dole out money for species conservation. They are embracing an approach called "triage" or "prioritization," which relies on calculations of where the biggest benefit will come from spending. The story of Canada's woodland caribou offers a look at why some scientists are calling for triage, and the wrenching choices involved. Proponents say it can benefit the most species with limited funding. But the strategy has critics, who charge it threatens to strip money from some of the neediest cases--species on the brink of extinction that might be saved only with costly, last-ditch efforts.