Ecological and Conservation Correlates of Rarity in New World Pitvipers

Rare species tend to be especially sensitive to habitat disturbance, making them important conservation targets. Thus, rarity patterns might be an important guide to conservation efforts. Rabinowitz's approach defines rarity using a combination of geographical range, habitat specificity, and local abundance, and is frequently used in conservation prioritization. Herein, we use Rabinowitz's approach to classify the New World (NW) pitvipers (family Viperidae) regarding rarity. We tested whether body size and latitude could predict rarity, and we compared rarity patterns with extinction risk assessments and other prioritization methods in order to detect rare species not classified as threatened or prioritized. Most NW pitvipers have large geographical ranges, high local abundances, and narrow habitat breadths. There are 11.8% of NW pitviper species in the rarest category and they occur along the Pacific coast of Mexico, in southern Central America, in the Andean region of Ecuador, and in eastern Brazil. Rarity in NW pitvipers is inversely related to latitude but is not related to body size. Our results indicate that additional species of NW pitvipers are threatened and/or should be prioritized for conservation. Combining complementary approaches to detect rare and threatened species may substantially improve our knowledge on the conservation needs of NW pitvipers. (AU)