Indirect impacts:

Walls and fences tend to cut through animals home ranges; fragmenting the habitat and splitting the population in this way can cut off access to mates, causing genetic isolation and inbreeding. Borders can also restrict access to vital resources - particularly a problem for large bodied migratory species or those with large ranges, such as bear, lynx, deer, sheep, big cats and wolves - leading to hunger and dehydration. The end result, major population reductions or even sudden mass moralities.

"But wildlife friendly borders exists, along highways and man made waterways, surely they will make country borders wildlife friendly?" - perhaps not, the ultimate goal for border control is that barriers are impenetrable with designs that reflect this, including underground metal walls and electric fences. In the name of national security the consequences toward wild roaming species do not tend to take high priority in the planning process. In Arizona 37 environmental protection laws have already been renounced (including the Endangered Species Act and the Wilderness Act) in order to strengthen security along the border with Mexico.

Direct impacts:

111 miles of razor wire fencing has already been erected along one-third of the frontier between Slovenia and Croatia. Found in the barbs along the fence have been a slew of mangled deer carcasses. The grim and painful deaths of animals caught up in border fences has been reported all over the world; from giraffes, elephants and the highly prized sable antelope found dead in Botswana to dead argali (mountain sheep) caught up along the border fence in Tajikistan.