What Happens to a Dead Animal in Nature? How Death Feeds an Ecosystem

When an animal dies in the wild, its story is not over. Within hours, a whole community of living things moves in, and the body’s materials start a new life in the soil and in other animals. Ecologists have studied this closely, because it is a key part of how ecosystems recycle.

Who arrives first?

Usually the larger scavengers. A Nebraska wildlife magazine says the first visitors to a carcass are generally big scavengers, such as a golden eagle. Next come the insects. Beetles are among the most important: the magazine notes that there are 18 species of carrion beetles in Nebraska alone. After flying to a carcass, a carrion beetle drops to the ground and starts burying it, which removes the animal from competition with other scavengers.

Who does most of the work?

Flies, bacteria, and fungi. Research from the Australian National University says flies are the main arthropod consumers of animal carrion. The Nebraska magazine calls bacteria and fungi the true engines of decomposition, because they break complex materials down into simpler compounds such as nitrogen, phosphorus, and carbon. Fungi and microbes can even dissolve hard tissues and slowly release their nutrients back into the ecosystem.

What is a cadaver decomposition island?

It is a spot of enriched soil where a body has decomposed. A review in the journal Naturwissenschaften describes a dead mammal as a high-quality resource that releases an intense, localized pulse of carbon and nutrients into the soil. The result is a concentrated “island of fertility.” These islands are linked to more soil microbes, greater microbial activity, and more nematodes (tiny worms). They are also a specialized habitat for certain flies, beetles, and early-growing plants, which increases biodiversity.

How much dead animal matter is there?

More than most people expect. The same review says that as much as 5,000 kilograms of cadaver may enter each square kilometer of land every year. It also describes cadaver decomposition as a neglected area of study, and the Australian team adds that the role of dead animals in nutrient cycling is poorly understood or downplayed compared with the role of dead plants.

How long does the effect last?

For a long time. The Nebraska magazine says the nutrients released by a decomposing carcass can nourish the soil for weeks, months, or even years, supporting plant growth and soil fertility. The Naturwissenschaften review calls each island a temporary natural disturbance that releases energy and nutrients to the wider ecosystem.

Do scavengers help or compete with microbes?

Both, in a sense. Researchers at Wageningen University describe a race between scavengers and microbes the moment an animal dies. They think nutrients recycle faster when an ecosystem has many scavengers, because scavengers can spread nutrients over a much larger area than microbes can. This is a hypothesis they are testing by excluding some scavengers from carcasses in a nature reserve.

What does this have to do with people?

Human bodies decompose by the same basic processes, which is why scientists study them at facilities like those in Body Farms: How Scientists Study Human Decomposition. The idea of returning a body to the earth is also behind Green and Natural Burial. For what happens to a human body, see What Happens to Your Body After You Die.