The main objection to developing the oil resources in the Arctic National Wildlife Refuge (ANWR) is the potential impact on the Porcupine Caribou herd that migrates through the area. The arguments are made in terms of broad generalities, along the lines of “caribou are in the same area, so they are threatened.” If one tries to quantify the threat, is turns out that perhaps 1% of the herd might be impacted in some way, but the actual reduction in the herd size is probably a good deal less.