By Benjamin Gurin
The importance of migration
Migration, the seasonal movement of a species from one place to another, is an important adaptation for many of Earth’s inhabitants. Plants and animals migrate for various reasons. Many plants move seasonally to different habitats that support their growth. Animals often migrate with the change in weather to more hospitable environments for food sources, breeding, and raising young. It is also important for animals to travel to other regions to find mates. The pairing of mates from different populations increases gene variability, a necessary factor in the long-term survival of a species.
All around the world, migratory animals face a growing array of threats, including habitat destruction, overexploitation, disease, and global climate change. Nonmigratory species also face such threats, but migratory animals seem especially vulnerable because of the long distances they travel. Their populations can be harmed not only by the loss of breeding habitat but also by changes in their wintering grounds and stopover sites. Many are forced to change their migratory patterns, and some are no longer able to migrate at all.
Monarch butterflies, for example, migrate up to nearly 3,000 miles (4800 km) each year. Native to North America, Monarch butterflies can’t survive within cold conditions so they travel to the southern part of California and Mexico during winter. Every year, a new generation makes the trek. Monarchs spend most of their lives migrating (2-3 months), but each generation often hibernates in the same trees as the last one. The disappearance of their usual trees disrupts their migration, along with many other human caused threats.
Migration more critical with climate change
Due to the planet’s ever-changing climate, a larger percentage of the world’s species are migrating to find livable habitats, and at faster rates than before. Plants and animals are forced to migrate because of increasing temperatures and other climate changes such as sunlight and precipitation.
A tally of more than 4,000 species from around the world shows that roughly half are on the move. The ones on land are moving an average of more than 10 miles per decade, while marine species are moving four times faster. Some individual species are moving far more quickly. Atlantic cod and Europe's purple emperor butterfly, according to Camille Parmesan, a scientist at Plymouth University in the United Kingdom, moved more than 125 miles in a single decade.
The altered migration of a given species, either by distance traveled or by length of time it occupies a region, negatively impacts all life forms higher on the food chain, which rely on synchronic timing with that species for survival. Proof of this lies in the increased mortality rate of the Caribou in Greenland. The plants they rely on for sustenance are now at their peak at an earlier time of year. Many of the plants have already died before the caribou arrive at their breeding grounds in the summer, and are therefore unavailable to provide them with food.
Take another example of climate change’s impact on fellow species. Shrubs in the 19th century stood just over three feet. As temperatures warmed with fossil fuel emissions, and growing seasons lengthened, the shrubs multiplied and prospered. Today many stand over six feet.
Bigger shrubs drew moose, which rarely crossed the Brooks Range before the 20th century, followed by snowshoe hares. Both have become part of the subsistence diet for indigenous hunters in northern Alaska, as melting sea ice makes traditional foods like seals harder to chase. Altering migration patterns such as these make the need for wildlife corridors all the more pressing.
How land development disrupts migration
In East Africa, 1.4 million blue wildebeests start their 1,500-mile clockwise migration in January, congregating on the Serengeti’s southern plains and traveling through the national parks of Kenya and Tanzania. Zebras and gazelles join the wildebeests’ quest for the rainy season that leads to more plentiful food reserves.
Apart from crocodile-infested rivers, hungry lions, and human hunters, the world’s largest mammal migration could find its way blocked by the new threat of roads. A planned Serengeti highway would connect human populations west of Lake Victoria with populations east of the national parks, but it could also disrupt the animals’ travel corridors. Fences to keep the animals off the highway could stop them from reaching vital food and water sources.
The roads and buildings that block migration passages threaten plants and animals who are unable to cross. Fortunately, there are many groups and organizations that are fighting for the rights of these species by advocating for the protection of wildlife corridors.
Why are Wildlife Corridors important?
Saving the great migrations will be an important conservation challenge of the 21st century. One solution to this problem is wildlife corridors.
Wildlife corridors are legally sanctioned passageways that facilitate the migration of plants and animals. With the ever-growing development of highways, buildings, and other human-made structures, they make it possible for species to travel between habitats without being blocked by traffic and other obstacles.
Corridors may also help facilitate the re-establishment of populations that have been reduced or eliminated due to random events (such as fires or disease). This could also balance some of the worst effects of habitat fragmentation, where urbanization divides habitat areas and deprives animals of both their natural habitat and the ability to move between regions to survive.
Wildlife corridors are vital for the survival of a multitude of migratory species.
Some wildlife corridor victories
In a recent win, a proposal was passed to combat the growing rate of mountain lion fatalities due to highway traffic in and around Ventura, California. The Ventura County Planning Commission voted on January 31st, 2019 to establish and preserve wildlife corridors to protect mountain lions and other migratory species. In addition to building wildlife crossing structures and buffers around lakes and rivers, the plan will also limit outdoor lighting and fences. The “Habitat Connectivity and Wildlife Corridors” proposal will be reviewed in March and implemented if the Ventura County Board of Supervisors votes yes.
As an innovative interpretation of wildlife corridors, wildlife bridges were built in Banff National Park in 1997 across the Trans Canada Highway to reduce car-wildlife collisions. Since then, the mortality rates of large carnivores are 50 to 100 per cent lower along the overpass and underpass sections of the highway. In those same areas, there is currently a nearly 0 per cent rate of vehicle-related elk deaths, compared to 100 per year in the mid-1990s. Tony Clevenger’s research concluded that in Banff, 11 species of large mammals have used the structures over 200,000 times, including the hoary marmot, wolverines, lynx, garter snakes, boreal toads, beavers, and red fox.
In June 2018, Mass Audubon sanctioned 110 acres of land in Plainfield, MA. This wildlife corridor is connected to the West Mountain Wildlife Sanctuary, which spans 10,000 acres. It is a key addition to a network of protected land, and serves as an important bridge for many migrating large mammals.
Many environmental organizations including WWF Nepal, along with donor agencies and local citizens, collaborated with the Government of Nepal to establish The Terai Arc Landscape in 2001. It covers 14 different protected areas in India and Nepal. The grasslands, forests and river valleys provide key habitats for many species including rare Indian rhinos, Asian elephants and Bengal tigers. The Terai stretches from the Bagmati River in Nepal to India's Yamuna River.
A 28-kilometer wildlife corridor with an underpass was built in the mid-2000’s in Mt. Kenya beneath the major A2 Nanyuki Highway. This underpass provides critical connectivity between Mt. Kenya, a World Heritage Site, and Borana, Kisima, Ngare Dare and the northern Lewa Wildlife Conservancy. Since then, numerous elephants have safely crossed under the major road without endangering themselves or motorists, and without damaging crops.
Current Challenge: The Mexico/U.S. Border Wall
The Mexico/U.S. border includes hundreds of miles of public lands and six national parks. This land and its inhabitants will all be put in jeopardy with the Trump administration’s proposed building of a Mexico/U.S. wall along the 2,000 mile border. Coyotes, mountain lions, wolves and other inhabitants of the Chihauhan desert will be cut off from their natural migration patterns. Many of the species that will be affected are endangered.
Several governmental and non-governmental groups are conducting studies to assess the full impacts the wall would have around the Rio Grande river in Texas, where construction is expected to take place. Several environmental organizations including the Center for Biological Diversity, Defenders of Wildlife, and Animal Legal Defense Fund have filed lawsuits against the Trump administration for waiving multiple environmental regulations in the interest of the wall.
How Earth Law Can Help
The legal establishment and protection of wildlife corridors embody the ideals of Earth Law, or Rights of Nature, which focuses on a holistic, eco-centric view of the world. Earth Law recognizes that humans can only be healthy if Nature is healthy. With bodies like the United Nation’s Harmony with Nature initiative, the International Union for Conservation of Nature all working towards evolving laws to strengthen the protection of nature – the global movement is growing.
Nations like Ecuador and Bolivia have amended their constitutions to recognize Right of Nature. Earth Law Center is working with local partners to submit national constitutional amendments in Mexico and El Salvador as well as working for rights of rivers and oceans.
Earth Law Center is building an international movement from the ground up, one that gives better grounding to the idea that humans have a responsibility for how we impact the world around us. The belief that nature - the species and ecosystems that comprise our world - has inherent rights has proven to be a galvanizing idea, and we work with local communities to help them organize around the rights of nature to protect their environment from the threats that they see.
The heart of the ELC approach is to seek legal personhood for ecosystems and species, a designation similar to that given to corporations in U.S. law, and one that if done well will imply both rights for the entities so designated and responsibilities on the part of human beings and societies to respect those rights.