Range contractions of the world's large carnivores

Abstract

The majority of the world's terrestrial large carnivores have undergone substantial range contractions and many of these species are currently threatened with extinction. However, there has been little effort to fully quantify the extent of large carnivore range contractions, which hinders our ability to understand the roles and relative drivers of such trends. Here we present and analyse a newly constructed and comprehensive set of large carnivore range contraction maps. We reveal the extent to which ranges have contracted since historical times and identify regions and biomes where range contractions have been particularly large. In summary, large carnivores that have experienced the greatest range contractions include the red wolf (Canis rufus) (greater than 99%), Ethiopian wolf (Canis simensis) (99%), tiger (Panthera tigris) (95%) and lion (Panthera leo) (94%). In general, the greatest range contractions occurred in Southeastern Asia and Africa. Motivated by the ecological importance of intact large carnivore guilds, we also examined the spatial extent of intact large carnivore guilds both for the entire world and regionally. We found that intact carnivore guilds occupy just 34% of the world's land area. This compares to 96% in historic times. Spatial modelling of range contractions showed that contractions were significantly more likely in regions with high rural human population density, cattle density or cropland. Our results offer new insights into how best to prevent further range contractions for the world's largest carnivores, which will assist efforts to conserve these species and their important ecological effects.

Keywords: carnivore guild; geographical range; historic; intact guild; livestock; predator.

Figure 1.

Range contraction maps for 25 large carnivores. Regions of persistence (i.e. inside both historic and current ranges) are shown in yellow-orange, while regions of contraction (inside historic but not current range) are shown in dark red. Species are ordered by percentage range contraction with the greatest contractions shown in the uppermost panels.

Figure 2.

Percentage of historic range lost for each large carnivore. Carnivores names are coloured by population trend (red, decreasing; black italics, stable; blue underlined, increasing) and bar colours indicate carnivore endangerment status.

Figure 3.

Composite range contractions maps based on all 25 large carnivores. Variables shown are (a) historic species richness, (b) current species richness, (c) their difference (i.e. lost species richness) and (d) the percentage of species lost.

Figure 4.

Current and historic species richness histograms by region of the world. ‘Asia’ excludes Southeastern Asia, which is shown separately. Vertical lines indicate mean richness. Panels are sorted by difference in mean richness and indicate that the most extensive range contractions (by this metric) occurred in Southeastern Asia, Africa and the rest of Asia. Overlap between current and historic range histogram bars is shown in dark purple.

Figure 5.

Regions of the world with intact or no longer intact large carnivore guilds (one or more species). Note that regions with high historic large carnivore richness (like Southeast Asia) seldom have intact guilds. Altogether, intact guilds make up 34% of the world's land area while 96% of land (excluding Antarctica) once contained one or more large carnivores.