Sonoran Pronghorn Release

The rugged 660,000 acres of Kofa National Wildlife Refuge is perfect habitat for reptiles.  But it’s also home to mountain lions, bighorn sheep, mule deer, and now (as of December) Sonoran pronghorn.

Sonoran pronghorn (sometimes called antelope) are an endangered subspecies that inhabit the Sonoran Desert in southwest U.S. and into Mexico.  A captive breeding program at Cabeza Prieta National Wildlife Refuge has helped stabilize and increase their numbers, even allowing some to be returned to the wild.  Recently, however, several of those captive pronghorn were brought to Kofa National Wildlife Refuge, a refuge complexed with two others, including Imperial National Wildlife Refuge where we have volunteered the past seven years.

Ideal Habitat

Kofa’s rugged countryside may have once been home to Sonoran pronghorn and appears to be ideal habitat.  To prepare for the pronghorn arrival, Kofa staff surveyed and contracted the preparation of a 320 acre section of the Refuge, outlining it with a six-foot chain link fence obscured with a shade covering and surrounded with two rows of electrified wires to exclude predators and retain pronghorn.

Delivery date was set for Wednesday, December 14, and we looked forward to helping with or at least observing the operation.  Starting out early that morning, we drove 45 miles up the highway to the turnoff onto a dirt road leading another 18 miles to the pronghorn enclosure, the last mile of which required our high clearance 4-wheel drive refuge vehicle.

Delay

Along the way, we were notified that the delivery time was delayed due to snow that grounded the helicopters in their home base at the Grand Canyon.  At the pen site, we waited with Kofa NWR’s manager for word of progress.

As we waited, we entered the huge one-mile by one-half-mile enclosure that would soon be home to a dozen rare Sonoran pronghorn, smaller and lighter in color than their northern counterparts.  Within the enclosure were two pens the size of a large tent, each covered with a blue quilted tarp.  The plan called for a helicopter carrying two anesthetized pronghorn and two veterinarians to land close to the fence.   Each pronghorn would be transported on a stretcher to one of these small pens where medical personnel would administer a reversal drug and allow the animal to recover in darkness before being released into the large enclosure.  Six trips would deliver 12 pronghorn.

Because it had rained the night before, the blue tarps sagged and pulled away from their clasps.  When we entered one of the small pens, the stench of damp canvas greeted us.  “It smells like scout camp,” Chuck mused.

Maintenance

After securing the tarps with rope, we walked the perimeter of the fence to check for problems.  The radio came alive with the announcement that the helicopters had departed, but encountered stormy weather and returned to the Grand Canyon airport.  The airlift would be postponed until Thursday.

 

Arrivals

The next day, Thursday, after morning obligations, we arrived in time for the third helicopter drop.  Because of a late start, this was the final delivery of the day.  The helicopter approached from the south and passed by before circling back and landing from the north a hundred feet from where we stood.  Dust and wind forced us to turn our backs to it and hold onto our hats.

 

 

 

Kofa staff rushed to help unload and carry the first stretcher from the helicopter into the small pen within the large enclosure.  As they entered the blue tarp-covered pen, they placed the pronghorn doe on the ground and slid the stretcher from beneath her.  A delicate animal, the pronghorn was anesthetized to endure the flight.  A blindfold covered her eyes.  A strap secured her legs.

 

The veterinarian in charge of this animal knelt on one side to remove the bag of saline solution attached to the animal to keep her hydrated and untie the bindings on her legs.  The Refuge biologist and a vet tech assisted from the other side.  Working quickly, the team tossed aside the bag and administered a reversal drug to counteract the anesthesia.  We stood nearby, recording vital information – time of helicopter arrival, time of animal arrival into pen, time of release from pen into enclosure, ear tag color and number, radio collar color, temperature of the animal. Then, closing the door after themselves, everyone left except the veterinarian who remained to monitor the pronghorn as she recovered her senses.

The door opened a bit, and the blindfold was tossed outside.  Soon the veterinarian emerged from the cage, jacket coated with pronghorn hair.  She closed the door behind her, leaving it open just enough to peek in and view the progress of the awakening animal inside.  The blue tarp flinched with sporadic thumps from within.

Release

When satisfied that the pronghorn was ready for release, everyone stood to the side of the cage as the veterinarian pushed the door open.  The doe emerged slowly, wobbled a bit, and staggered toward open spaces.  She stopped to stare at us with large, uncomprehending eyes.  She took another step, circled, and eyed us again.  Eventually she tottered away and disappeared from view.

In the meantime, the second pronghorn underwent similar preparations for release.  When she too was out of sight, the helicopter pilot announced that this was the final flight for the day.  The rest of the animals would come Friday, two per helicopter, three helicopter flights.

Since several of the Kofa staff would be unable to attend the next day, we were asked to return to assist with the remaining flights.  Some time ago we had been told that we would probably not even be able to see the pronghorn, much less be involved with the project.  Consequently, the invitation to come another day delighted us.

Final Flights

Friday brought windy weather, so Chuck created a wind sock out of strips of caution tape, secured it to a PVC pipe, and slid the pipe over the Suburban’s antenna to help the helicopter pilots judge their landing strategy.  With fewer of us on hand, we were called upon to help tote the stretchers, as well as assist in preparing the animals once inside the tarp-covered cages.  For the first time in my life, I touched a live pronghorn.  Then the vet tech asked me to hold the animal’s head as she went about her tasks.  With the doe’s head in my hands, I realized how strong these animals can be.  The weight of the head caused me to prop my arms on my knee.  And as she struggled to regain her senses, I struggled to hold her head in the proper attitude.

After the third and last flight of the day departed, the large enclosure was now home to ten pronghorn does and two pronghorn bucks.  An underground catchment collects rainwater to supply two small water tanks.  Eventually irrigation will enrich forage for the pronghorn; but in the meantime if extra feed is needed, hay is on hand to be placed in racks designed to hold it off the ground.  A 1000-foot well has been dug in case of drought.

As of delivery date, the enclosure and surrounding area of nearly 1000 acres is closed to the public.  For the first few months, someone will check on the pronghorn every day, even spending nights in the remote area for a period of time.  An observation tower has been set up near the enclosure, but offers limited view.  The pronghorn have much space and many depressions where they can hide.

History in the Making

“This is a historic event!” exclaimed the biologist, as excited as everyone else to be a part of this transition.

When the pronghorn begin producing young and the herd has grown, eventually some will be released into the wild.  In the plans for many years, this project will last for many more years.

“So when can we hunt them?” someone joked.

Kofa’s manager was quick with her response.  “That would be the epitome of recovery when you can hunt them.  That would mean success!”

Betty and Chuck

 

2 thoughts on “Sonoran Pronghorn Release”

  1. Pronghorn and their prehistoric ancestors are my area of study. I envy you this experience! What a wonderful priviledge to be able to interact with the pronghorn “up close and personal”.

    Reply

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