The lion, Panthera leo, is synonymous with power and majesty. As an apex predator, the adult lion sits at the top of its food chain, yet its existence is fraught with danger from its earliest days to its final years. The species is currently classified as Vulnerable on the IUCN Red List of Threatened Species, a status that reflects the significant threats it faces across its remaining range. Factors determining a lion’s survival are complex, involving conflicts with other wildlife, the pressure of disease and aging, and, most prominently, the escalating impacts of human activity.
Mortality from Predation and Interspecies Conflict
Threats to a lion’s life often come from within its own ecosystem, particularly during its vulnerable cub and subadult stages. Inter-species conflict is a frequent cause of death, with spotted hyenas acting as a major competitor and predator of young lions. Hyenas actively target isolated cubs, and older lions are sometimes killed by large groups when they are weak or injured.
Intra-species conflict is another devastating source of mortality, specifically male lion infanticide. When a new coalition of males takes over a pride, they systematically kill any unweaned cubs to bring the lionesses back into estrus, ensuring they sire the next generation. This destabilizes the pride’s social structure and is a significant factor in high cub mortality rates.
Adult lions, while having few true predators, frequently suffer fatal injuries during hunts. Confrontations with large prey like African buffalo or giraffe can result in severe goring, crushing injuries, or broken limbs. These wounds often lead to permanent disability, infection, or the inability to hunt, resulting in starvation.
Causes of Natural Mortality
Beyond the direct violence of conflict, natural factors contribute to a lion’s death, with disease and aging being primary concerns. Viral pathogens such as Canine Distemper Virus (CDV) have caused devastating epidemics in lion populations, such as the 1994 outbreak in the Serengeti that wiped out over a third of the lions there. The virus causes neurological disease and pneumonia, but its most severe effect is weakening the immune system, making the lion susceptible to secondary infections.
Bovine tuberculosis (bTB) is another serious threat, transmitted primarily through consuming infected prey, particularly African buffalo. It is closely linked to reduced breeding success and longevity in affected prides. Many lion populations also carry Feline Immunodeficiency Virus (FIV), which further compromises their ability to fight off diseases like CDV and bTB. Parasites such as the blood protozoan Babesia can also become lethal when a lion is immunocompromised by a virus or environmental stress.
Aging, or senescence, ultimately reduces a lion’s ability to survive in the wild. Older lions struggle to maintain the speed and strength needed to take down large prey, which often leads to starvation. Environmental stressors, such as severe drought, compound this issue by reducing prey abundance and concentrating lions around scarce water sources. Drought conditions can also lead to lions scavenging on tick-infested carcasses, increasing the transmission of diseases like Babesia.
Direct Human-Caused Mortality
Direct human actions are now the single greatest cause of mortality in many lion populations, often resulting from intentional killing. The most frequent cause is retaliatory killing, which occurs when lions prey on domestic livestock, leading to Human-Wildlife Conflict (HWC). Local communities, seeking to protect their livelihoods, often resort to lethal methods to eliminate the threat.
A common and highly destructive method of retaliation is the use of poisoned carcasses, which can indiscriminately kill an entire pride and other scavengers that feed on the same bait. Lions are also frequently killed by snares and gin traps, which are often set for bushmeat but accidentally injure or kill large carnivores. Even if a lion escapes a snare, the wire can remain attached, leading to fatal injuries or death by infection.
Targeted poaching for the illegal wildlife trade is a growing threat, where lions are killed specifically for their body parts, including bones, teeth, and claws. These parts are often used in traditional Asian medicine as a substitute for tiger products, driving an unsustainable trade. Furthermore, legal trophy hunting, while regulated, often targets prime adult males. The removal of these dominant breeding males destabilizes the pride, frequently triggering infanticidal takeovers by new males, causing a cascade of mortality within the social group.
Systemic Human Threats to Survival
Systemic human pressures create an environment where lion survival is increasingly difficult. Habitat loss and fragmentation reduce the available space for lions, as natural areas are converted for agriculture and human settlements. This isolates lion populations, preventing gene flow and making them vulnerable to inbreeding and disease outbreaks.
This loss of territory forces lions into closer proximity with people, creating “ecological traps” where available prey lures them into high-risk areas. Prey depletion exacerbates the conflict, as the natural prey base is reduced through the illegal bushmeat trade and competition with domestic livestock. With fewer wild animals to hunt, lions are more likely to turn to cattle and goats, fueling retaliatory killings by local herders.
Infrastructure development, such as roads and railways, acts as a physical barrier that fragments the landscape and can cause accidental deaths. These barriers restrict the movement of both lions and their prey, increasing pressure on resources and intensifying human-lion interactions. These systemic threats reduce the ecosystem’s carrying capacity, making lion populations less resilient to all other causes of mortality.