Graph of the Day: Worldwide population estimates of large-carnivore species

10 January 2014 (Science) – Worldwide population estimates of large-carnivore species. Error bars represent the low and high range of the estimates when available. Population estimates were not available for all species. Species ranges vary widely, and range sizes can have a strong influence on species population levels (table S1). Sources: Gray wolf (90), all other species IUCN (91).

Maps showing the the spatial overlap for the ranges of large-carnivore species by threat category for habitat loss and fragmentation, persecution, utilization, and depletion of prey. The number of large-carnivore species affected by specific threats is shown in the map legend. Threat categories include: (A) Habitat loss and fragmentation. Forest logging and/or the development of urban, agricultural, and road infrastructure reduces land available to large carnivores and creates barriers between and within populations. (B) Persecution. Culling (poison baiting, trapping, and shooting) for the purpose of removal or reduction, in some cases reinforced with a government-subsidized bounty system, in response to real or perceived threat to pastoral and agricultural activities and human lives. (C) Utilization. Large carnivores are killed for sport, body parts for traditional medicine, fur, and meat for human consumption, and live animals are captured and sold. (D) Depletion of prey. The decline of prey populations due to human hunting, competition with livestock, habitat loss, and other factors reduces the prey base for large carnivores. See table S2 for raw data. Source: IUCN (91).

Large-carnivore species list, body mass (in kilograms), diet, endangerment status, population trend, and percent of historical range occupied. Body masses are from Gittleman (15), Mammalian Species Accounts, and the Animal Diversity Web. Diet categories are from Hunter (1) as follows: M, meat eater; V, vegetation and/or fruit eater; O, omnivore. Species status and trend are from the IUCN Red List (16): LC, least concern; NT, near threatened; VU, vulnerable; EN, endangered; CR, critically endangered. *Changes to taxonomic status have influenced the number of species included in this group, and some less-known and taxonomically ambiguous carnivores may be missing from this analysis because they have yet to be listed by the IUCN. †Currently incorporates the New Guinea singing dog, C. hallstromi, whose taxonomic and conservation status is yet to be elucidated.

ABSTRACT: Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around the world. We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest mammalian carnivores on Earth. Consistent with theory, empirical studies increasingly show that large carnivores have substantial effects on the structure and function of diverse ecosystems. Significant cascading trophic interactions, mediated by their prey or sympatric mesopredators, arise when some of these carnivores are extirpated from or repatriated to ecosystems. Unexpected effects of trophic cascades on various taxa and processes include changes to bird, mammal, invertebrate, and herpetofauna abundance or richness; subsidies to scavengers; altered disease dynamics; carbon sequestration; modified stream morphology; and crop damage. Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately determine the fate of Earth’s largest carnivores and all that depends upon them, including humans.

Status and Ecological Effects of the World’s Largest Carnivores