Human-generated litter poses a significant threat to wildlife worldwide. This debris, including discarded plastics, metals, and fishing gear, enters virtually every habitat. Animals often mistake the waste for food or become physically trapped by it. While the mechanisms of harm are documented, accurately determining the total number of animals that die each year from litter is complex. The scope of the problem prevents the establishment of a single, precise global mortality figure.
The Difficulty of Calculating Animal Mortality
Obtaining a single, authoritative number for annual wildlife mortality from litter is not feasible due to numerous ecological and logistical challenges. Most deaths occur unseen by humans in remote or deep-sea environments, making direct counting impossible. Carcasses often decompose quickly or are scavenged, and many animals die far offshore, sinking before they can be recorded.
Quantification relies heavily on localized studies, stranding data, and mathematical models, which produce widely varying estimates. These figures are often extrapolated from the impact on specific populations, such as the millions of marine animals affected annually by plastic pollution. This reliance on fragmented data means any reported number is a conservative estimate of the true global impact, reflecting monitoring limitations. Reports citing up to one billion seabirds killed by litter every year illustrate the massive scale of the issue.
Lethal Mechanisms: Entanglement and Ingestion
Litter kills animals through two primary physical processes: entanglement and ingestion. Entanglement occurs when animals become snared in plastic loops, six-pack rings, discarded fishing line, or netting. This trapping restricts movement, making it difficult for the animal to hunt, flee predators, or reach food and water.
Entanglement injuries often result in deep wounds that can lead to severe infection, amputation, or chronic pain. For marine animals, entanglement frequently causes drowning or strangulation as the debris tightens around their necks and bodies. Ingestion happens when wildlife mistakes litter, such as plastic fragments or balloons, for a food source due to its smell or appearance.
Once consumed, the litter can cause blockages in the digestive tract, preventing nutrient absorption and leading to a false sense of satiation. This results in starvation as the stomach fills with indigestible material, or it may lead to poisoning from toxic chemicals leaching from the plastic. A study of stranded juvenile green turtles found that 86% had ingested plastic, demonstrating the widespread nature of ingestion.
Marine Litter: The Biggest Death Toll
The ocean environment experiences the highest documented rates of litter-related mortality due to the immense volume of plastic pollution that accumulates there. A particularly lethal form of marine debris is “ghost fishing gear,” which includes abandoned, lost, or discarded fishing nets, lines, and traps. This gear, mostly made of durable plastics, can continue to “fish” indiscriminately for years, trapping and drowning marine life.
It is estimated that between 500,000 and one million tons of ghost gear enter the ocean annually, making up at least 10% of all marine litter. This debris harms 66% of marine mammal species, 50% of seabirds, and all seven species of sea turtles. Ghost gear has driven species like the vaquita porpoise to the brink of extinction due to entanglement in illegal gillnets. Microplastic ingestion is also pervasive, as filter feeders and smaller organisms consume fragments, allowing them to bioaccumulate and transfer up the food chain to larger predators.
Practical Steps to Reduce Wildlife Death
Individuals can take steps to mitigate the death toll caused by litter, starting with the proper disposal of all waste. Never littering and participating in local cleanup efforts are the most immediate ways to remove harmful debris from the environment. Securing household garbage and recycling bins with tight-fitting lids prevents scavenging animals from accessing waste that could be toxic or cause entanglement.
Reducing the use of single-use plastics is an effective preventive measure, as is correctly preparing waste items before disposal. For instance, plastic six-pack rings should be cut apart, plastic bags should be tied or cut, and cans should be rinsed and crushed to prevent small animals from getting trapped inside. Responsible handling of fishing line and tackle is important, as this debris is one of the most common causes of entanglement and ingestion in aquatic and terrestrial wildlife.