For wildlife, huge difference between different kinds of agriculture

We live in an increasingly human-dominated world, where once-intact native habitats are being rapidly fragmented into smaller 'islands' surrounded by a hostile 'sea' of human land-uses.  But for wildlife, not all human land-uses are equal.

  Bobcats like having trees overhead

Bobcats like having trees overhead

A recent study in southern California shows that the bobcat, an important but shy wildlife species, is affected very differently by different types of farming.

Like most species, bobcats must move to survive.  Animals trapped in small habitat fragments live in populations too small to be viable.  Bobcats are therefore far more likely to survive if human-dominated lands surrounding habitat fragments are 'permeable' to their movements.

One way to make fragmented landscapes more permeable is to create movement corridors linking the fragments together -- what some have called "bandages for wounded landscapes". 

Another way is to use less-hostile types of agriculture that pose less of a barrier to sensitive species.  For bobcats, it turns out that orchards pose considerably less of a barrier to movements than do intensively cultivated row-crops such as maize, soy, and sugar beets.

Bobcats used row crops only rarely, and even then tried to dash through them quickly, evidently feeling highly vulnerable.  However, their movements in orchards were much more relaxed and similar to those in native habitats.

Studies in the tropics have similarly shown that agriculture that retains tree cover is often much more benign for nature. 

In the New World tropics, for instance, birds, bats, and many other species tend to be much more abundant in shade-cacao plantations (used for producing cocoa), where larger trees are retained or grown to shade the cacao trees, than in more intensively used lands. 

  Bare-eyed antbird, an understory specialist in New World rainforests

Bare-eyed antbird, an understory specialist in New World rainforests

Wildlife diversity is especially high when native tree species are retained in the shade-cacao plantations, rather than using exotic fruit or timber species.  Another big bonus for wildlife is having native forest nearby the shade-cacao plantation.

However, shade-cacao is not a panacea for tropical species.  The most sensitive wildlife, such as understory birds, rarely use cacao and are mostly restricted to native rainforest.

The bottom line: native habitats are always the best, but when agriculture is unavoidable, not all types of farming are created equal.  Understanding how different farming methods affect wildlife -- and which wildlife species are most vulnerable -- will give us a leg up for managing and conserving nature.