Habitat fragmentation

Habitat fragmentation is specific to the breaking up of a natural environment or patches of vegetation into smaller, disconnected sections. It is generally a consequence of agricultural activities, road building or housing developments. A complex web of flora and fauna requires an abundance of resources: food, air, water, sunlight, and the right habitat to survive.  Devastation, degradation, and fragmentation of ecosystems caused by human development means that natural habitats, resources, and species are becoming highly limited and cut off from each other. For a species to sustain themselves successful breeding must take place. But when there is nowhere to live, resources are scarce and mates are difficult to find, they need to adapt or face the possibility of dying out.

Where is habitat fragmentation happening and what are its effects?

The effects of habitat fragmentation are varied throughout the globe, yet they impact a wide range of natural habitats and species.  Here are some examples:

Natural Parks are abundant in Italy with over 20 National Parks and about 140 regional parks covering 10% of the land surface.  However, Cinque Terre, Abruzzo, Lazio and Molise National Parks are where the natural habitat fragmentation, due to transportation infrastructures, is much higher.

In the Brazilian Amazon, research has shown that fragmentation within Amazonia has led to changes in forest dynamics, structure, composition, and microclimate, making remaining spaces highly vulnerable to droughts and fires; not to mention intensive hunting within fragmentation further threatening wildlife populations.

Intertidal wetlands and mangrove forest habitats are also at risk. In Southeast Asia, a global hotspot of mangrove loss, research found conversion to aquaculture and rice plantations the biggest drivers of loss and fragmentation.

The benefits of Wildlife Corridors in action

Species known to use wildlife corridors include deer, elk, moose, bears, mountain goats, lizards, tortoises, sheep, wolves, big cats, and elephants.  From the smallest insects to the largest land mammals, the meekest prey to the most cunning of predators; wildlife corridors can help species find food, sanctuary, and safe passage to a new home.  Here’s just a few examples of wildlife corridors in action:  

The Bee Highway in Norway was constructed in 2014 by the urban guild of beekeepers: ByBi. The “pollinator passage” stretches from Holmenkollen in the north west, to Lake Nøkkelvann in the south east. This project initiated measures such as green roofs, flower-emblazoned cemeteries and strategically placed beehives to make it possible for the bees to find resting places and food almost anywhere in Oslo.

The American Flyways signify the 4 unique aviation routes of migratory birds across the whole of the United States: the Pacific, Central, Mississippi and Atlantic Flyways. Birdlife International is working to help the 350 migrant species that breed in North America and head south for winter by creating lasting conservation partnerships across national borders.

In Australia in 2017, the Rainforest Trust established a 173.5 acre called the Misty Mountain Nature Refuge.  The corridor is vital for animals (such as the near threatened Lumholtz’s Tree Kangaroo) to move freely between two large expanses of World Heritage rainforest. The trust is currently installing 17,000 locally sourced plants over the next two years to widen the corridor.

Successful Wildlife Corridor stories

One of the biggest success stories of wildlife corridors has to be the Yellowstone to Yukon Conservation Initiative (Y2Y). This impressive 2,000 mile (3,200 kilometre) stretch connects Canada’s Yukon Territory to the Greater Yellowstone ecosystem via North America's Rocky Mountains.  More than 450 partner groups have joined forces since 1993 to support the shared mission and vision of creating an interconnected system of wild lands and waters, harmonizing the needs of people with those of nature.

This ambitious cross border corridor features several natural ecosystems; housing wolves, wolverines, lynx, cougars, golden eagles, and bull trout; with one of the connections allowing grizzly bears to naturally re-occupy the Salmon-Selway wildland complex in central Idaho. Saving wildlife and humans from road collisions is a key part of the project as the region already has more than 100 under and overpasses. 

As well as protecting the area to maintain and restore habitat integrity, Y2Y seeks to support environmental and social justice and oppose actions and policies that undermine human diversity, equity, and inclusion principles.

Do Wildlife Corridors actually work?

Although public opinion, conservation groups and conservation policy may appear supportive of wildlife corridors, biological scientists have long argued the pros and cons.  Whilst this has already wasted precious time, especially at the rate we are losing habitats and species, a recent study which concludes 18 years of research, could serve to end the argument once and for all.

Using long-term data from a large, replicated experiment, Damschen et al. (2019) show quantitatively how corridors reduced the likelihood of plant extinction in patches by about 2% per year and increased the likelihood of patch colonization by about 5% per year.  Connected patches had 14% more species than unconnected patches. The study concludes: “Restoring habitat connectivity may thus be a powerful technique for conserving biodiversity, and investment in connections can be expected to magnify conservation benefit.”

With robust science backing up the notion that connectivity is key in ecosystem health and biological diversity: what lies ahead?  Typically, investment in wildlife corridors has been minimal, yet when we think about the future, we must consider the increasing pressures climate change will have on our Earth’s biodiversity. Wildlife corridors have been suggested by the Australian government as a strategy to contribute to the resilience of the landscape in a changing climate and help to reduce future greenhouse gas emissions by storing carbon in native vegetation. Not only could more wildlife corridors help strengthen biodiversity, but they could be an important part of climate change mitigation.