I love covering conservation efforts in the field. Seeing the practical applications of scientific theory is always fascinating, and the chance to be around people working to make a positive difference is inspiring as well. It’s even better when wildlife is involved. That’s why I was excited to be sent by the Nature Conservancy to shoot efforts to reintroduce pygmy rabbits into the Beezley Hills Preserve in Central Washington.
I have to admit I had never heard of pygmy rabbits before. It turns out they are quite unique. They are the smallest rabbits in the world, with adults weighing about a pound (less than half a kilo). They are one of only two rabbit species in North America that dig their own burrows. They are only found in the shrub-steppe regions of the western United States, and their diet consists mainly of sagebrush. Sagebrush is usually toxic for most mammals, but these rabbits have evolved a larger than normal liver to accomodate the toxin.
Unfortunately, the rabbits are also quite rare. Populations are dwindling due to habitat loss caused by development, invasive species, and fires. One genetically distinct population in Washington state, the Columbia Basin pygmy rabbit, was listed as an endangered species by the federal government in 2003. A recovery program was started by the Washington Department of Fish and Wildlife (WDFW), along with others, with the intention of breeding and then eventually releasing the rabbits into the wild.
Trying to bring back a rabbit population close to extinction is a complicated process. I got a taste of that on my visit as I documented several stages of the reintroduction effort. WDFW scientists, along with university researchers and volunteers, were planning on first capturing some pygmy rabbits that were being bred and raised in a semi-wild environment. The rabbits would then be taken to the Nature Conservany’s Beezley Hills Preserve to be released into the wild.
We all met at the breeding pen at sunrise, to catch the rabbits before the day could heat up. Jon Gallie, a WDFW wildlife biologist, told me that pygmy rabbits were very sensitive to heat and stress, and sometimes did not survive the move. Traps were distributed to everyone, and we all fanned out to look for the rabbit burrows that dotted the pen.
Each burrow usually contains many entrances, so burlap bags were stuffed into all but two to limit access for the rabbits. Traps were then placed at the remaining two openings, with one being placed facing inward towards the tunnel, and the other facing outward. This way rabbits both entering and exiting could be caught. Burlap sacks were also used to camouflage the traps, and to minimize the animal’s stress once caught.
Plastic tubes in the breeding pen were also checked. They had initially been placed there as artificial burrows until the rabbits could dig their own. Eventually, rabbits began to be caught.
The six that were caught included both adults and juveniles, proving that the rabbits were actually breeding inside the pen. A temporary work station was set up at the site, and each rabbit was examined to determine it’s sex, weight, and overall health status.
DNA samples were also taken from the ear of each new capture, to establish a genetic database of all individuals. This can also be used to determine the genetic diversity of the population, which is a good indication of the health of the species.
The rabbits’ genetic health has been a concern for years. A 2003 survey discovered that the number of Columbia Basin pygmy rabbits in the wild had dropped below 30, which is an insufficient number to maintain a genetically healthy population. A rescue team captured 16 of them and tried to breed them in captivity, but were unsuccessful. Eventually it was deemed necessary to introduce pygmy rabbits from nearby states into the breeding program to increase genetic diversity and numbers.
That helped. Captive breeding was more successful, and 20 offspring were released into the wild. None survived. It was then decided to attempt more natural breeding, with juveniles being born and raised in protected, semi-wild pens near the release site. This effort resulted in more positive survival rates, with one 3 year study indicating juvenile survival rates averaging 12% (DeMay et al., 2017). According to the WDFW, that is close to the normal survival rate of 15%. The juveniles that we were capturing, therefore, were of mixed lineage. The last genetically pure Columbia Basin pygmy rabbit died in 2008.
Finally, microchips were inserted in a few captives for ID purposes. The $8 price tag for each microchip made it impossible to tag every captured rabbit. The rabbits were then placed in plastic tubs to be transported to the release site. A bit of sagebrush was added to help reduce stress.
The release site nearby had been prepared the day before, by WDFW biologists and volunteers. A temporary fence was erected to keep out terrestrial predators, such as badgers and coyotes, until the rabbits were able to dig their own burrows. Then the fence would be removed.
The fence construction included a horizontal element as well, making a cross section of the fence look like an upside down “T”. This was to prevent predators from digging under the fence from the outside, and the rabbits escaping from the inside.
The rabbit tubs were loaded on a truck and driven the short distance to the release site. After about 7 hours in the field we were all getting tired, but excited by the thought of seeing the rabbits released. All that was left to do was lift the lids and watch the results of all our efforts.
Some of the rabbits hesitated, giving us one last look and a chance to say goodbye. Then they left the bucket for a life on their own.
Unfortunately, I have some bad news. A fire swept the shrub-steppe of Central Washington recently, and most of the Columbia Basin pygmy rabbits in Beezley Hills died. WDFW staff and firemen worked hard to save 32 rabbits, but over 80 did not survive. Fortunately, there are still about 70 rabbits in other enclosures, plus 75-100 in the wild in the Sagebrush Flats Wildlife Area. It’s a big setback, but the recovery efforts by WDFW, the Nature Conservancy and others will continue. For more information visit Hope Persists for Pygmy Rabbits Despite Blaze.