have been recorded at anywhere from high, in the highest cases on top of the tree canopy. Tree species is unimportant with the eagles seeming to prefer any type that is difficult to climb, such as those that have thorny branches, few lower branches or smoother bark. In Kalahari Gemsbok National Park of South Africa, almost all nests were in the highly thorny, Acacia-like tree, Vachellia erioloba, in savanna areas. Most nests in southern Africa often are at a height of less than . Often trees used are on the sides of cliffs, ridges, valley or hilltop, with one nest having been found within a cave. In the karoo of South Africa, they have also nested on electric-power pylons. Locally, with the sometimes epidemic levels of clear-cutting of old-growth trees, such pylons may provide a fairly suitable alternative that the eagles can utilize in absence of woodlands. The nest of the martial eagle is a large and conspicuous construction of sticks. In the first year of construction, the nest will average in diameter and measure about deep. After regular use over several years, the nests can regularly measure in excess of in both diameter and depth. The nest may be lightly lined with green leaves. The central depression of the nest averages about across. The nest of martial eagles average slightly smaller than those of crowned eagles and, compared to other large eagle tree nests, are much broader than they are deep, relatively, especially when newly constructed. The construction of new nests can take several months and, in some cases, pairs can take up to two months where they appear to return to the nests daily but contribute only green leaves to line the nest. The repair of an existing nest takes on average two to three weeks. Most pairs will usually just use one nest (as opposed to temperate-zone eagles which may have several alternate nests), with up to 21 years of continuous use for one nest recorded, but pairs constructing a second nest are not infrequent either. One exceptionally prolific pair built or repaired 7 nests during 17 years in Zimbabwe, although they only nested 5 of the 17 years. Martial eagles have a slow breeding rate, laying usually one egg (rarely two) every two years. Clutches of two have only been reported only in South Africa and once in Zambia, and the younger sibling probably never survives