What animals eat dead animals

Carcasses in the wild increase biodiversity

Death has many faces. The body of a stag that has just been shot is still intact, you can see the shiny fur and the beauty of the creature. If, on the other hand, the stag was carried away by hunger or cold in a harsh winter, the picture is different: the body emaciated, the ribs protrude - every bone is evidence of the privations of life. After death, the various stages of decay and utilization occur: Large scavengers such as wolves or white-tailed eagles first open the carcass. Now ravens, crows, magpies and foxes can attack the carrion and fight over the best chunks. If the dead animal is quickly found by carnivores, there won't be much left of it after a few days. If the carcass remains undetected, it is populated by thousands of flies and beetles and their larvae in a very short time. Decay sets in later. The carcass stinks to high heaven before there isn't much left but clean bones and a few hairs.

It is the cycle of life, the eternal change of growth and decay, as it naturally takes place all over the world - if you let it. In contrast to the few large wilderness areas that still exist in the world, hardly a carcass is left lying in Germany. Animal owners, hunters and veterinarians ensure that the carcasses are removed as quickly as possible. For disease prevention. But probably also because the sight of the carcasses in the landscape is undesirable.

Study object red deer carcass

Death can bring forth a lot of new life. In a study published in early 2020, the Dutchman Roel van Klink researched how many and which types of red deer carcasses can benefit. In 2013, in Oostvaardersplassen, one of the largest nature reserves in the Netherlands, he and his colleagues examined five such carcasses over a period of several months. (The wilderness area attracted attention because more than 1,000 horses, cattle and deer starved or froze to death in the harsh winter of 2017/2018.)

"We wanted to know whether the carcasses have a direct positive effect on the diversity and abundance of different insect and spider species and other arthropods," says van Klink. The team assigned the locations where the one-month-old carcasses were to a comparative area with similar conditions, for example in terms of vegetation or soil quality. Traps were installed in all ten locations, in which the arthropods were counted weekly for over six weeks. The result: The researchers found three times as many animals in the carcasses as in the comparison areas; As expected, the number of carrion-eating species in particular was significantly higher.

Five months later, the scientists examined the areas again. The now dry carcasses were high overgrown with thistles. The plant biomass there was five times as large as on the areas without dead animals. Some of the minerals and nutrients from the carcasses had entered the soil and used as fertilizer to accelerate plant growth. The large amount of plant growth in the direct vicinity of the dead deer was also attractive for many insect species: more than four times as many arthropods were caught in the carcass areas than in the control areas. And the carcasses also had a clearly positive influence on biodiversity: around two and a half times as many species were counted in their vicinity as at the comparison points. The proportion of scavengers had fallen sharply in late summer. Instead, many herbivorous species were found - and also predatory species, which in turn targeted herbivores. "The study shows that carcasses have a positive effect on the biomass of plants and insects and also on biodiversity," says Roel van Klink. Carrion that remains in the landscape can therefore play an important role in counteracting insect death and promoting biodiversity.

Numerous species benefit from carcasses

In Germany and in other countries, however, hardly any use is made of these possibilities: "To this day, large carcasses are extremely rare in the wild," says René Krawczynski. Only if deer, roe deer or wild boar accidentally perish in an inaccessible place is there a chance that the carcasses will remain in the landscape. Krawczynski is the pioneer of carcass research in Germany. As part of the Necros project at the Technical University of Cottbus, he studied for many years which vertebrates use large carcasses directly or indirectly and, together with colleagues, set up test areas in Brandenburg, Baden-Württemberg and the Netherlands.