“Finding nests in Kruger National Park is hard – we are hampered by thick bush and a huge study area. We started monitoring nests in 2011 after an aerial survey which located 22 nests. Over the years of monitoring we have found new nests incidentally while working in the park, many just visible from roads with a keen eye, and aerial surveys were carried out again in 2015 and located a further 17 nests. However, as the years passed, we also lost nests. The trees that some were in fell down, the nest itself collapsed or the eagles simply stopped visiting some nests. These nests have become a big interest to us; have the eagles built another nest in their territory that we don’t know about or have the eagles themselves gone too?
The only way to find this out was to get a bird’s eye view of the rest of the territory around each of these nests. With the support of the Bateleurs (not the bird, but a group of pilots who fly for the environment) we did just that and took to the air to start to figure out the answer for this question. I met our volunteer pilot Marlon Lewinsky and his 1964 Cessna 182 at the Skukuza air base on 28 July and together with Gareth Tate (EWT) we hit the runway. We set up our surveys in blocks around the location of 22 ‘lost’ nests and flew 10km transects up and down each block looking out for new nests. The Cessna offers good views below and we had an observer on each side of the aircraft, but you only have once chance and in areas with lots of trees our eyes scanned each one wildly looking for nests. Each time we spotted one we could bank around and take a GPS location and record the species of tree the nest was in to try and make it easier for us to relocate the tree from the ground later. Unlike vultures which make a relatively flatter nest right on top of the canopy, Martial Eagle nests are generally in the highest major fork of a tree. They are large stick structures unlike any other, but from the air it’s hard to judge the size of the sticks and I’m sure we have some smaller eagle nests like those of African Hawk Eagles and perhaps some vultures jumbled up in our locations.
We flew transects like this for eight days, generally taking off in the early morning or late afternoon to avoid the warmer temperatures around the middle of the day which make the ride bumpy. In total we covered 2700km of transect flying, and recorded an astonishing 70 nest locations. We also sighted 15 Martial Eagles from the air, of which 3 were juveniles. Now our next task begins… we will have to revisit these locations on foot to work out which of them are really Martial Eagle nests and which are still active; despite our surveys being during the middle of the breeding season we saw very few with eagles actually on the nest. Some of the locations were clustered and may also represent alternative nests of the same pair. So although we can’t yet answer our original question of how many pairs of eagles have built another nest in their territory versus how many territories are no longer occupied, we are a step closer
A huge thank you to the Bateleurs and pilot Marlon Lewinsky for making this dream a reality. Alongside being important fieldwork, it was a spectacular opportunity to see Kruger from the air and get a deeper perspective of our field area. Our gratitude also to Jaco Mol and the SANParks Airwing unit at Skukuza, who supported our project enthusiastically while working tirelessly to further conservation in the park and ensure a safe airspace for us to work in. Thank you also to Lindy Thompson (EWT) who helped as an observer, and to Sharon Thompson (SANParks) who is always on hand to help with project logistics and maintain smooth running for us within Kruger”
— Dr. Megan Murgatroyd
This project is made possible by The FitzPatrick Institute, HawkWatch International and The Endangered Wildlife Trust, in collaboration with The Bateleurs.