Tomorrow, March 3, we’ll recognize the eighth World Wildlife Day, which was proclaimed by the United Nations General Assembly (U.N.G.A.) at its 68th session on December 20, 2013. This annual day of recognition is meant to celebrate the planet’s wild animals and plants, and to raise awareness about the many benefits that their conservation provides to people. According to the U.N.G.A., “The animals and plants that live in the wild have an intrinsic value and contribute to the ecological, genetic, social, economic, scientific, educational, cultural, recreational and aesthetic aspects of human well-being and to sustainable development.”
Of course, as wildlife and environmental enthusiasts, you and I know the “worth” of the wild animals with whom we share the world. But I want you to consider a more unusual “take” on the value of wildlife on this particular March 3: the advantages they continue to give us even after they have died.
On a forest walk, when you come across a tree that has fallen, you can immediately see its still strong importance. Often, you’ll spot fungi, mosses and other small plants growing out of this “nurse log” and colonies of insects, communities of amphibians and a variety of birds inhabiting the dead wood. In terms of biodiversity, you could almost say that the tree is more “alive” than ever. Forest managers have learned that it’s usually better for the life that follows to leave trees where they die. And now, scientists are beginning to understand that animal carcasses left in an environment play a similar, vital role in the functioning of ecosystems and in maintaining biodiversity.
The problem is, many of us are not comfortable coming upon carcasses on our nature hikes, walks or wildlife excursions. For the planet’s health, will we ever be able to accept dead animals on the landscape, as we have for plants?
All ecosystems need death
The fact is that all ecosystems need death. It’s almost a nature-documentary cliche: a migrating herd of wildebeests approaches a rushing river. The first bold animals cross, followed by the rest of the herd. But crocodiles lurk, and many of the wildebeests don’t make it to the other side. Their bodies end up feeding scores of animals in and around the river; their deaths enabling the survival of others. In fact, scenes such as this—or a lion kill or a cheetah chase—are some of the most exciting events to witness on an African safari.
But in most ecosystems, only up to 10 percent of existing organic matter is consumed by animals. The remaining 90 percent remains uneaten and turns into decomposed organic matter called detritus.
That detritus can cause a whole, new ecosystem of plants and animals to develop around the carcass, with the body at its center.
Animal carcasses are more nutrient-rich than most plants, and they break down faster. Decomposers convert those nutrients into biologically useful forms, allowing diverse plants to grow near the carcass, which become food for herbivores.
In the summer months, especially, thousands of small invertebrates (including 750 species of beetles, 150 species of flies and a large—though unknown—number of ants, butterflies, grasshoppers and wasps) benefit from the remains of a dead animal. For many species of arthropods, carrion is an essential habitat for a specific developmental stage. This multitude of flying and crawling organisms, in turn, is an abundant buffet for insectivorous amphibians, birds, mammals and reptiles.
So, these carcass-based, mini-ecosystems are extremely dynamic. At first, different organisms visit a carcass at different stages of decomposition, so one dead animal can support great diversity over the course of its decay. Moreover, while the conventional picture of a carcass is something large, such as an antelope or a dead moose, insects and other small creatures die, as well. Soil is full of small invertebrates; the continuous deaths of these short-lived creatures can help nourish plants on an ongoing basis.
All plants seek nutrients
Science studies back this up. In a report published in the science journal PLOS ONE in January 2020, researchers from the German Center for Integrative Biodiversity Research in Leipzig, Germany, and from the University of Groningen in the Netherlands found that carcasses not only provide food for many carrion-eating animal species, but that their nutrients also contribute to the significantly increased growth of surrounding plants. This, in turn, attracts many herbivorous insects and their predators.
In the Oostvaardersplassen nature reserve in the Netherlands, one of the largest wetland areas in Central Europe, scientists investigated how red deer carcasses impact local biodiversity. First, they recorded the presence of insect species on surfaces both with and without carcasses. They then measured plant growth in the immediate vicinity of a carcass. They found that the bodies of red deer are not only advantageous to many carrion-eating insects, such as carrion beetles or flies, they also have a positive, long-term effect on plant growth.
Plants, such as the welted thistle, grew more than five times larger near the carcasses than in other locations, resulting in a fourfold increase in the number of herbivorous insects and their predators.
The whole planet calls for trees
One of the main conservation strategies recommended by experts to combat climate change is reforestation. Having more trees encourages the uptake of additional carbon within our atmosphere, and carcasses boost plant growth on the forest floor.
Therefore, as we aim to move towards a cleaner, greener planet, relaxing the regulations on removing carcasses from conservation areas and nature reserves could increase the reproduction of trees; a natural way to tackle our climate emergency.
But is that possible?
We all benefit from life—and death
Not so long ago, the scientific and pro-ecological communities had to work hard to sensitize state authorities and society to the role that dead wood plays in natural, forest ecosystems. Many of us today regard seeing fallen, decaying trees in the forest as a good sign.
Although dead animals are as vital a source of life as dead trees, we find it much harder to accept their presence. The sight of them across natural landscapes is still a social taboo. In Europe, laws are strict; and within conservation areas, regulations support the removal of carcasses as a precaution against disease transmission and because they’re unpleasant for visitors to look at.
But across Europe, scavenger species—such as hyenas, vultures and some species of beetles—have become endangered. Their declines have been caused by habitat fragmentation and the loss of predators, which provide carcasses by hunting prey. Carrion has largely disappeared from European ecosystems and is no longer part of the natural life cycle. Many European vultures, for example, are fed artificially; without that, they would not be able to survive.
On our own continent, semiwild farm animals are subject to agricultural laws, the bodies of wild herbivores that are part of the hunting economy do not stay on the landscape and animals hit by cars are immediately disposed of by road managers. Therefore, large animal carcasses are a scarce resource.
The resulting small amount of carrion in the environment is a huge loss. Carcasses, especially in winter, play important roles in the diets of young, inexperienced animals who still have little success in obtaining food on their own. Bodies of dead animals are also a good source of energy for those individuals in a growth period—who need a lot of it in a short time—such as ravens.
On World Wildlife Day, I know that this isn’t the most pleasant or usual way to think about the wild animals with whom we share the planet. But I do think that we honor them the most when we appreciate all that they do for us, in life and after it.
Here’s to finding your true places and natural habitats,