A black eagle

FOUR years ago the Walter Sisulu National Botanical Garden had a crisis. Their magnificent Black Eagle male disappeared and it was thought that a 40-year old breeding programme would come to an end.

But the female eagle took charge. She disappeared for several days, and reappeared with a young male, and the pair have continued breeding ever since.

The Garden, some 30 kilometres west of the city centre at Roodepoort, is one of a network of eight botanical gardens around the country. It consists of around 300 hectares of landscaped and natural veld areas, planted with only indigenous trees, 600 species of indigenous flowering plants and shrubs. Over 230 species of birds have been recorded in the Garden as well as a number of reptiles and small mammals.

The kilometre walk to the top of the waterfall is worth it to get a view of the eagle's nest

The Garden, donated to the people of Roodepoort in 1982 by the farmer who owned the property, is crisscrossed with trails, one going to the top of one of two small mountains that overlook a waterfall and the eagles' nests. Other walks take the visitor past the wild flower garden, a fern walk, a forest walk along the spruit, or a walk down to one of three dams on wheelchair-friendly brick and wood paths, to sit in the hide to watch the water birds.

There's more - an arboretum with shady lawns, a water-wise demonstration garden, acres of green lawns, a cycad garden, a magico-medicinal garden (plants used for magical and medicinal purposes), a succulent garden, and environmental education.

The eagle pair have two nests, towards the top of the beautiful 70-metre Witpoortjie Waterfall in the Gardens, and each year they alternate between them. The pair mate for life, and every year around March they prepare the nest when new sticks are added and a nest cap of leafy twigs is made. The male performs spectacular courtship displays, and two eggs are laid around mid-May, four days apart.

Magnificent gardens filled with indigenous flora, as far as the eye can see

After 45 days an all-white chick hatches and once the second chick is laid four days later, the "Cain and Able" struggle begins. The first chick, Cain, proceeds to kill Abel, the second chick, over the next 3-4 days.

The white plumage changes to a golden brown over the next 90 days, when the bird leaves the nest. This juvenile will spend the next three months in the gardens, being fed by its parents. During this time it practises and perfects its hunting and flying techniques, and in mid-December or January it will leave to establish its own territory. The chick has an estimated 30% chance of survival in its first year.

At around 4-5 years the eagle develops its beautiful dark plumage, then finds a mate and establishes its own territory.

This breeding pair are one of the few in an urban environment, and are unique to the Witwatersrand area, although they are under stress because of urban encroachment on their natural environment. This pair live mainly on hares and guinea fowl, although traditionally black eagles eat mostly dassies.

The Botanical Garden is a people place. It has a busy programme of events throughout the year. These include a spring plant fair, with thousands of indigenous plants on sale; picnic concerts throughout winter, featuring a variety of light classical and jazz performances on alternate Sunday afternoons; stargazing in early September and October, and a solar eclipse breakfast in early December; a teddy bear's picnic in early October; a clivia display in September; and carols by candlelight in December.

The Garden also boasts a restaurant, the Café Clivia, under two stinkwood trees and alongside a water garden with a series of ponds and water-loving plants; the Random Harvest Indigenous Nursery, with a variety of plants on sale at reasonable prices; and a curio shop.

There are a number of ongoing projects to maintain the excellence of the park. Control of alien invasive plants, especially along the streams that run through the park, is ongoing and labour-intensive; the continued fencing of the park, especially with the acquisition of more land; maintenance of walkways and trails; and further educational signage and labelling of plants and trees.

The Garden has big plans for the future, including a conservatory and display glasshouse to house plants from other regions in the country; a concert stage; a climate garden illustrating various aspects of climate and how it affects plants; a wildlife-friendly garden demonstrating how to attract birds and other plant life into the garden; a geological garden displaying geological diversity of the region by means of boulders of different rock types; and a fragrance garden linking to the magico-medicinal garden, particularly planned for the blind and poorly-sighted.

The Garden has a special programme for the Summit, including an "Africa's plants & people" exhibition and lecture series; a Sunday picnic concert featuring the Buskaid Soweto String Project; and a clivia display, as well as various activities for children. (Full programme is available on line)

A nineteenth century picnic party poses for a picture at Witpoortjie Waterfall

If you don't have the energy to walk to the top of the waterfall and look down on one of the eagles' nests, stop at the thatched entrance hut: there's a webcam focused on the nest, and you can get an eagle's eye view of it.

THE Witpoortjie (Afrikaans for "white gate") Waterfall got its name from the nearby Witpoortjie Station, where Johannesburgers disembarked for a day's outing at the falls, in the late 1800s.

• Visit the Walter Sisulu National Botanical Garden website