Keeping an eye on our environmental treasures
The monitoring of the breeding performance of the Crowned Eagles on Sappi plantations forms part of a wider populationmonitoring programme in Mpumalanga which has been in progress since 2005.
The question may be asked: why is a forestry company interested in promoting an understanding of Crowned Eagle population dynamics in and around their plantations? The answer is simple. Being at the top of the food chain, a lot can be learned about the health of the forest ecosystem, and the dynamics of the animal populations living within the planted/natural landscape, by simply observing the behaviour of these great predators. Grey duiker, for example, are plentiful within the plantations, and appear to be an important part of the Crowned Eagle’s diet. Although habitat transformation is listed as a threat to the survival of most plants and animals, Crowned Eagles appear to use the plantation habitat effectively. By keeping a finger on the pulse of a top predator, Sappi hopes to gain valuable information that will help forestry limit their impacts and promote synergy between production and conservation.
Crowned Eagles are magnificent raptors that can sometimes be spotted in the skies above Nelspruit and the surrounding area. They are large birds, with a wingspan of up to two metres and can weigh in the region of three kilograms or more, depending on whether they are male or female. They are territorial and may nest in a variety of big forest trees such as Cabbage trees, Matumis and frequently in large Eucalyptus trees. They form life-time partnerships and in forest habitats, tend to raise a chick every second year, caring for the fledgling for up to eighteen months after hatching. Annual breeding has been observed in savanna environments and seems to be influenced by a number of factors, including availability of prey.
Based on many years of observations, it has been established that there are approximately 43 nesting sites known to occur in the greater Nelspruit area, an area ranging from Malelane in the east, Dullstroom in the west, Graskop in the north to just below Barberton in the south Not much was known about breeding success of these birds and what impact habitat alteration was having on populations of Crowned Eagles. As 20 of the 43 known nests were found to occur in timber plantations of which 11 were on Sappi Forests property, it gave Sappi the opportunity to support a monitoring project.
Photos: Dr Garth Batchelor