By Sarah Webb and Michele Hofmeyr
©© Martie Pelser and Sarah Webb
Seeing the Kruger National Park (KNP) from the air really puts the size of the park into perspective. It is amazing to see how big two million hectares really is. Winter is the time of the year when the KNP census team takes to the air to count the animals living in this two million hectares. Trained staff from Sanparks scientific services conduct the annual aerial census throughout the KNP from north to south using a fixed-wing Cessna 206.
The census, the 21st, started in Pafuri on Monday July 16, 2007 and the team completed the last areas in the south of the KNP on July 27, 2007. The animals that were counted are impala, giraffe, kudu, waterbuck, warthog, zebra, wildebeest and white rhino. The team also noted incidental sightings of black rhino, ostrich, sable, tsessebe, eland, roan, and steenbok.
A black rhino census has already been completed earlier in the year. The current census technique for plains game is called "distance sampling." In 1977 when animals were first counted from the air, they didn't use the distance sampling technique. The census involved flying the entire area of Kruger in an attempt to count every animal.
It took the team three and a half months to complete the census each year. Logistically and financially this level of total coverage was not sustainable and the team started to use the distance sampling technique. This technique means that the entire area does not have to be flown but rather selected transects across the park.
It was statistically calculated that the most cost effective way to get the best estimate of the animal numbers in the park is to fly an average of 27 percent of the KNP. To achieve this, 109 aerial transects are flown in an east-west direction throughout the KNP.
The Census Team
©© Martie Pelser and Sarah Webb
The census team consists of eight people – six people in the aircraft and two ground support staff, Johan Baloyi and Obert Mathebula. This year the aircraft team included; pilot, Dr Ian Whyte, Sarah Webb as the data recorder, and four observers carefully spotting game from the windows – Dr Richard Fynn, Adolf Manganyi, Martie Pelser and Trust Mathoto. Chris de Villiers also assisted for a few sessions.
Martie Pelser says that, “It was a great opportunity to be involved in the census and something that I will never forget. You haven’t seen the Park if you haven’t seen it from the air, and I would like to thank everyone who was involved for an amazing experience.”
The team flew over 12 days for a total of 49 hours and 5842km. There were two full days and a few other sessions that the team wasn’t able to fly due to unfavourable weather conditions.
For this census, there needs to be clear weather as clouds cast shadows and it is very difficult to see game in a shadow, especially impala, kudu and zebra.
“It is a lot easier to see the darker animals, for example sable antelope and wildebeest”, explained Dr Ian Whyte, who has been working in the KNP for 37 years and retired at the end of July this year. Ian started with his first helicopter census in 1984 and with the fixed wing census in 1998. He has flown an amazing 10 fixed wing surveys and 23 helicopter censuses in his 37 years of service in the KNP.
Each observer has their window calibrated to suit their height and how they sit in the aircraft. There are four lines that are drawn on the window and these lines indicate distance from the aircraft when you are flying. In this instance, each line represents 100m on the ground, as each observer will be covering 400m at a time.
The four lines are named: A - alpha, B - bravo, C - charlie and D - delta. Alpha being within 100m, bravo within 200m, charlie within 300m and delta within 400m from the window of the aircraft. The observers call their respective sightings through the aircraft's intercom system for the data recorder to enter in the programme on the laptop, which is connected to the aircraft's Global Positioning System (GPS), in the sequence of species, number and strip.
For example, if 25 impala are sighted in the closest strip to the aircraft, the observer would call “impala, 25, alpha.” Each sighting that is entered into the programme, has the date, time, GPS point, species, number, strip, transect number and transect length (distance) recorded for it. The information that is captured has been given to Judith Kruger, the programme integrator: science support, as she analyses it and presents the final numbers for the census.
However, it is important to remember that this census does not give definite numbers as it is merely an estimate of the total population. This information provides trends in the population and this is very important for management purposes.
It definitely was a highlight for Ian to see Duke – the big tusker, on the final day of the census. Elephant and buffalo numbers are not included in this census because a completely separate census with the Sanparks helicopter is conducted in middle of August each year.