Columbia Basin's rolling landscape once covered in native sagebrush and bunchgrass stretching to the far mountains at the horizon is now a fractured landscaped invaded by cheatgrass, divided by highways and farming roads into a patchwork of wheat fields. This is the home of a diminutive rabbit the size of a grapefruit, the Columbia Basin pygmy rabbit (
Brachylagus idahoensis) which, but for human intervention, would not have made it into the 21st century. The last pure bred member of this isolated rabbit population died in 2008. Since 2001 captive breeding has kept the population hanging on in the Basin. Sixteen of the last few dozen members were captured then, and two decades of intervention followed.
Early in the program, the reproductive rate was slow and the offspring produced were sickly, perhaps due to inbreeding. University scientists and government biologists decided to perform a "genetic rescue" by hybridizing them with Great Basin pygmy rabbits from Idaho, a closely related population, in 2004. After that, things picked up and the smallest American rabbit began to reproduce--like rabbits. In 2009 the Oregon Zoo produced 29 kits. Unsurprisingly
the Zoo found that pairings based on familiarity and preferences resulted in greater breeding success than pairings based
only on genetic relatedness.
Breeding was transferred to semi-enclosed areas in the rabbits' native habitat, to aid their transition to release into the wild. Over 1300 kits were produced in the enclosures since 2011, allowing the release of over 1200 pygmy rabbits into the Sagebrush Flats Wildlife Area. On average, about 25% of the released rabbits' genome are wild genes. These genes reappear generation after generation because they produce traits that have survival value--natural selection at work. Thus, preserving the native pygmies from certain extinction rather than translocating another race was worthwhile work because it preserved genetic information coded by the unique ecosystem of the Columbia Basin.
 |
| credit: R. Bose for High Country News |
Successful emergency intervention has given the pygmy rabbit an uncertain future, however. It eats only sagebrush in the winter, and is only one of two species that digs its own burrows, beneath sagebrush.
[photo, left] Wildfires that proliferate due to fire resistant native vegetation being replaced by invasive species, can wipe out a recovering rabbit population. Fires occur now twice a decade instead of twice a century, the historic norm. The thirty thousand acre Southerland Canyon fire in 2017 destroyed most of the rabbit population living there. Breeding in enclosures has its drawbacks too--proximity promotes disease in the animals.
Consequently, expanding and preserving habitat is the key to reestablishing the species on a firm basis. The landscape is fragmented by human settlement. No one is suggesting humans move out, but some unneeded land can be set aside for habitat restoration and wildlife. There are Department of Agriculture programs that pay farmers to do that, and there are private organizations like Nature Conservancy that buy land solely for conservation. Stitching these separated parcels together with wildlife corridors would signify wildlife gain in
an era of global loss. To do that, cooperation from the human inhabitants is a necessary ingredient.
