Paths of Pachyderms
In Botswana, our busiest field season coincides with the drier months of the year. The rains stop in May, and by June, our winter, the leaves begin to drop, long grasses and vegetation disappear, and water slowly evaporates from the natural pans throughout the region. Soon the green, wet, lush landscape changes to a dry, barren environment, exposing the ground cover of the Kalahari’s thick soil.
Of course, this dramatic change influences the movements of wildlife, and vast numbers of herds work their way towards perennial rivers and adjoining floodplains. With congregations of elephant, zebra, buffalo, giraffe, and other wildlife along the rivers, it’s the prefect opportunity for people to witness and admire the majestic beauty of wildlife in Africa. For a conservation researcher it is also time to focus on efficiency for project priorities.
Elephants Without Borders has been deploying satellite-monitoring collars on elephants throughout northern Botswana for over 12 years, having tracked over 90 individual elephants; this is one of the longest and largest elephant movement studies in Africa. Collaring elephants involves many emotions, and it is wonderfully exciting.
Every individual pachyderm has its unique character and intriguing story to his or her own seasonal march, preferred routes, and favored places. Each new elephant fitted with a tracking device provides us with new information to understand the ecology of these animals. Unpredictable individual ranging behavior coupled with a dynamic, ever-changing environment in Botswana, underscore the need for long-term elephant studies.
We routinely track elephants from a fixed-wing plane, which allows us to visually assess collared elephants to determine herd structure and habitat use. These flights inspire us to push the boundaries of our research, and we often discover unusual occurrences that beg further questions.
Earlier this month, I was aerial tracking CH58, known as Naledi, a middle-aged bull who over the past two years of tracking has revealed to us an amazing new elephant route. He has been wandering seasonally between two very different eco-systems: the Okavango Delta, a large inland delta considered an “Eden” to wildlife; and Makgadikgadi National Park, one of the largest salt flats in the world. Other species are moving between these two systems as well.
It has been suggested that this long-distance migration route, also used by zebra and wildebeest, are ancient elephant paths. After many years, the government decommissioned a long fence line that separated these two ecosystems and severed any wildlife movements. Naledi was the first elephant to show us that the wildlife appeared to be re-establishing this migration route!
I decided that we needed to monitor Naledi longer than the usual four years, so we redeployed a second collar on him. Unfortunately, months later his satellite unit stopped transmitting, so I had to rely on the VHF in the unit to try to find him. Getting in the small Cessna plane to aerial track, I was quite nervous to discover what may have happened to Naledi. However, it didn’t take long to pick up his strong signal.
We followed the Boteti river system, which Naledi had been relying on for water in the arid salt flats. We searched elephant bulls diligently, hoping to sight one with the unit. To the team’s delight, we found Naledi 50 kilometers from where we heard his first VHF signal. He was only meters from the river, accompanied by a herd of 12 large bulls enjoying the cool waters and shady acacia trees that lined the river bank.
What intrigued me now was the sheer numbers of bulls we were seeing this far south in the center of Botswana. An electric fence along the Boteti River divides the protected national park from communal land, villages, and homesteads. The elephants had breached the fence, and many were on the communal side of the river, sharing resources with huge herds of cattle that roam the Kalahari plains.
I had heard rumors that the river’s new flow had moved as far south to an ancient dry lake, Lake Xau. We decided to fly further and follow the river as far as it flowed or until our fuel determined our turnaround point. I was astounded to see the extent of the river’s flow but also noted how quickly farmlands had developed as the river expanded south again. From the back of the plane, one of the team yelled out, “Elephants!,” and there was a herd of 18 large bulls at the southern-most point I had known them to ever be in the area. We continued south and saw more bull elephants!
I have a panoramic view of the landscape whizzing beneath my feet, left and right I have spectacular views of a vast landscape. My eyes scan the horizon. An hour’s flight from Maun, a fixed-wing spotter plane with four keen observers searching for elephants calls over the radio, “We have a group of 26 elephants, Mike, GPS coordinate are…” I smile, knowing sightings of these elusive bulls are difficult.
Through the hot mirage rising off the barren sand, I see the outline of a large herd of male pachyderms…they appear much larger than usual in this flat and shrubby desert. I hear Larry, our veterinarian, reach for his dart gun, a sign to Peter to begin dropping in altitude. Moments later we are fitting a collar to an impressive-sized elephant bull. Watching him rise, bearing a new GPS collar, I am hopeful that this device will help secure this arid habitat for these lumbering giants and unravel the mysteries of desert-roaming elephants.
Mike Chase, Ph.D., Director of Elephants Without Borders and Postdoctoral Research Fellow for the San Diego Zoo Institute for Conservation Research.