The Bateleurs rally to assist SAEON with aerial surveys

Planning the survey routes. From left: Alan Knapp and Gene Kelly of Colorado State University, SAEON’s Dr Tony Swemmer and Rodney Landela, a section ranger within the Kruger National Park (Picture courtesy of The Bateleurs) From the air the boundary is clearly discernible between Mopane trees, which dominate vegetation in the northern half of Kruger National Park, and the more typical bushveld of the southern half of the park. Ecosystems dominated by Mopane tend to be much less productive, contain fewer plant species, and support smaller populations of animals than the other major bushveld ecosystems (Picture by Dr Alan Knapp) Mopane-dominated vegetation gives way to riparian trees on the banks of the Olifants River (Picture by Dr Alan Knapp) The flight paths of flight 1, that tracked the length of the Olifant’s River (in dark red), and flight 2, which followed the Mopane boundary to the south (in green). For flight 2, the blue flags show patches of Mopane at the edge of its distribution, marked by a handheld GPS. Red flags show the location of sites subsequently located for collecting leaf and soil samples. (click to enlarge)

True to their slogan "Flying for the environment in Africa", The Bateleurs once again stepped in to assist SAEON with a crucial aerial survey.

Sponsored by The Bateleurs, the flight had a dual purpose - to identify suitable research sites along the southern boundary of Mopane trees (Colophospermum mopane) in the Kruger National Park (KNP), and to search for dead fish and crocodiles in a stretch of the Olifants River within the Park.

The mopane survey is aimed at assisting with the design of a scientific research project to better understand what factors control the current distribution of Mopane, and to make predictions about whether Mopane will spread southwards as global climate change intensifies.

Over the past two years, large numbers of crocodiles and barbel have been dying in a specific stretch of the Olifants River. The exact cause of these mortalities is not yet known, and rapid detection of new deaths is required to manage and research this phenomenon.

On the morning of Saturday 18th July, a visiting team of scientists from the USA as well as Rodney Landela - the section ranger for the Phalaborwa region of the Kruger National Park - were undeniably disappointed when they were informed that the planned flight for the day would be cancelled due to engine trouble.

However, Bateleurs pilot Jeremy Woods called an hour later to say the problem was fixed. After a few hours’ delay he arrived at Phalaborwa to meet the members of the research team which were hosted by Dr Tony Swemmer, Manager of SAEON’s Ndlovu Node. The Ndlovu Node is based at the Phalaborwa entrance gate to the KNP.

Discussion of the flight plans for two routes over Kruger soon began. Tony and Rodney participated in both flights to assist with navigation over the park.

On the first flight, the fourth place in the 4-seater Piper Commanche was taken by Dr Jesse Nippert, an ecologist from Kansas State University. It was decided to first check the Olifants River for dead fish and crocodiles.

Navigating for fish, crocodiles, eagles and vultures

Jeremy headed south from Phalaborwa airport and intercepted the Olifants River close to the western boundary of the Park. He then carefully navigated along the course of the river, flying at only 100 or 200 feet above the ground. While Jeremy kept an eye out for eagles and vultures, a potential danger when flying at that height, the rest of the crew scanned the river.

While hundreds of hippo were seen sunning themselves on the banks of the river, very few crocodiles were observed. Happily no dead crocodiles or fish were seen, but the low number of live crocodiles is cause for concern. No carcasses have been reported in the river since the flight and the results of this part of the mission confirmed that the spate of fish and crocodile deaths is over (for the time being).

For the second flight, Professor Alan Knapp, an ecologist from Colorado State University, joined Jeremy, Tony and Rodney, and again the flight initially followed the Olifants River eastwards. At the confluence of the Olifants and Timbavati rivers, they turned south and began to track the boundary between the Mopane-dominated vegetation and "Combretum-acacia" vegetation more typical in the south of the park.

Pinpointing the southernmost tip of the Mopane’s distribution

The time of the year turned out to be perfect for this exercise, as the orange-tinted leaves of the Mopane trees contrasted clearly with other tree species which had already dropped all their foliage. This made it possible to determine the southern boundary of the Mopane trees from the air (Photos 2 and 3). The extreme southern tip of the distribution of Mopane trees (in Africa) was located near Orpen Gate, and after circling this area, Jeremy put the aircraft on a course back to Phalaborwa.

A handheld GPS was used to map patches of Mopane along its boundary, and this information enabled the research team to find suitable research sites on the ground (Map).

At the sites located from the air, samples of Mopane tree leaves and soils beneath them were then taken, and the data obtained from the analysis of these samples will be incorporated into a research proposal that the team will be submitting to the National Science Foundation in the USA.

Large multi-national research project on Mopane distribution

If successful, the proposal will lead to the creation of a large research project that will run for a minimum of three years, and will involve both American and South African scientists. The project will focus on determining why Mopane trees do not occur any further south than they currently do, and whether they are likely to start spreading south as global climate change progresses.

Due to the large negative influence that Mopane trees have on the diversity of ecosystems in Kruger Park (and the neighbouring private nature reserves), any southward migration of this species will have important consequences for the ecotourism industry in the lowveld.

"We are extremely fortunate that SAEON has been able to tap into the services of a reliable outfit such as The Bateleurs to assist us in conducting aerial surveys," Dr Swemmer said. "Due to the vast areas of Kruger that are not accessible by road, it would have been impossible to identify good research sites along the Mopane boundary from the ground."

The survey also assisted SAEON and SANParks to get a bird’s-eye view of the particular stretch of the Olifants River where the spate of barbel and crocodile mortalities was experienced earlier.

"Aerial reconnaissance is a huge help in searching for dead crocodiles and fish in the more remote parts of the KNP," Dr Swemmer said.