Response to Human Development

We investigate impacts of anthropogenic activities across landscapes on wildlife population dynamics and distributions.

©Ashley Lutto/GWCC

Protected areas in North America: size matters

Protected areas are established for diverse conservation purposes, but their effectiveness for conserving species varies widely. We compiled studies that used telemetry to determine cause-specific mortality of North American mammals and compared mortality sources of animals monitored in areas classified as protected by the International Union for Conservation of Nature and non-protected areas. Protected areas in North America were associated with a 75% reduction in poaching mortality of mammals. Size of protected areas was also important; human-caused mortality on average decreased 4% with each additional 50 km2 in protected area size. The extent of mortalities and its consequences varies widely across protected areas based on specific human behaviors, species ecology, and population sizes. However, at a continental scale, protected areas reduce the proportion of poaching mortality of North American mammals and represent an important tool for wildlife conservation.

Effects of the human footprint

Over the Earth’s terrestrial surface, wildlife species are adversely affected by an increasing number of anthropogenic impacts to the landscape, collectively termed the “human footprint”. We conducted a synthesis of cause-specific mortality of North American terrestrial mammals, examining how traits such as human footprint of the study area, species lifespan, and diet interacted to influence anthropogenic mortality of mammals. We found that anthropogenic mortality of mammals increased with increasing human-associated impacts on the landscape, and that longer-lived species were affected more than their shorter-lived counterparts. These shifts in mortality can have substantial implications for understanding wildlife population dynamics and managing these populations across landscapes impacted by anthropogenic activities.

Increasing roads and vehicle mortality

Human development has resulted in an ever-increasing network of roads across Earth’s surface, with about 64 million km roads worldwide. Overall, collisions with vehicles may account for as much as 5% of direct terrestrial vertebrate mortalities worldwide. Although vehicle mortality is prevalent across all major species groups, mammals appear particularly vulnerable. We analyzed a database of North American mammal cause-specific mortality spanning 50 years to examine factors influencing vehicle mortality. Overall, vehicle mortality increased four-fold, from three percent in the 1960s to 12 percent by the last decade (2010s). Increased mortality caused by vehicles can adversely affect species and community dynamics, and reiterates the need for mitigation measures to improve conservation.