Ecological corridors: why animals need to be able to migrate

Animals need to be able to migrate

Animals and plants in the wild need enough habitat to survive. Many species migrate every year, such as birds, many fish and large mammals. Others have to leave their territory to find a mate or food. If nature areas are islands, populations become isolated. They become genetically poorer and can die out.

A nature area that is too small can be made viable by connecting it to another area through an ecological corridor: a wildlife bridge over a road, a natural riverbank or a strip of woodland. Together the areas give a species a real chance. Such a landscape is also more attractive for walking and cycling.

Waterways are important: the large rivers, but also the small ditches along the fields. Because of global warming, habitats are shifting. That makes it even more important that plants and animals can move along with them. If they cannot, they die out.

What blocks the way

Roads, fences, cities, dams and large farm fields block the way for animals. Livestock farming plays a special role. It takes up a lot of land for pasture and feed: in South America forests are cut down for soy and for cattle. It also pollutes the nature that is left.

Pollution does not respect boundaries

It is important to keep pollution out of nature areas. If food in nature becomes scarce or biodiversity declines because of pollution, animals have to look for food outside. Then they are more likely to become road casualties or to cause damage.

Factors that disturb nature are light, noise, fragmentation, mechanical and visual disturbance, changes in species, vibration, waterlogging, drought and, above all, eutrophication and acidification. These last two largely come from livestock farming: ammonia from manure is deposited on nature as nitrogen. Groundwater suffers as well. In areas with a lot of livestock, groundwater often contains more nitrate than the standards allow. Too much nitrate in drinking water is harmful to babies.

Animals know no borders

An ecological corridor only works if it continues on the other side of the border. That is why countries work together. In the European Union, the Natura 2000 network links protected areas in all member states. In Central America, the Mesoamerican Biological Corridor is to connect nature areas from southern Mexico to Panama. In North America, the Yellowstone to Yukon initiative works on a connected landscape from the United States to northern Canada.

Nature targets

In 1992 the United Nations Convention on Biological Diversity was signed. In 2010 the countries agreed that by 2020, 17 percent of the land should be protected nature. In 2022 this became 30 percent by 2030, on land as well as at sea. The European Union has the same target.

The fact that an area has been designated as nature does not mean it will actually become nature or that this will happen soon. A lot can still get in the way. Economic pressure keeps nibbling away at the plans and thus at the space for nature. Buying land is the most effective way to protect nature. Because land prices keep rising, buying sooner saves a lot of money.

Farmers can also contribute, for example with hedges and natural banks or by mowing later so that meadow birds can raise their young. In several countries they are paid for this.

Read also

• Why exporting meat and dairy leads to animal suffering: feed from other continents costs forests.
• International meat trade: why it increases animal suffering.
• Eating meat: the consequences for animals, environment, climate and world food.
• Can the honeybee survive in nature?