Primarily
nocturnal, giant elands have large home ranges and seasonal migration patterns. They form separate groups of males and of females and juveniles. Giant elands are alert and wary, making them difficult to approach and observe or to hunt. If a bull senses danger, he will give deep-throated barks while leaving the herd, repeating the process until the whole herd is aware of the danger. Giant elands can move quickly, running at over , and despite their size are exceptional jumpers, easily clearing heights of .
Diet Primarily a herbivore, the giant eland eats grasses and foliage, as well as other parts of a plant. In 2010,
histological analysis of the feces of South African western giant elands was done in the Niokolo-Koba National Park and in the Bandia National Reserve. In both studies leaves, shoots of woody plants, and fruits were found to be the three major components. The other components that appeared in minor proportions were
forbs and grasses, generally below five percent of the mean fecal volume. They were seen eating most foliage from
Boscia angustifolia,
Grewia bicolor,
Hymenocardia acida, and
Ziziphus mauritiana, and the fruits of
Acacia and
Strychnos spinosa. In the Bandia Reserve, differences in diet were marked among age classes. The conclusions were that in the dry season the eland was a pure browser, consuming grasses in small amounts.
Reproduction Mating occurs throughout the year, but peaks in the wet season. Females reach sexual maturity at about two years, and males at four to five years. A female can remain in
estrus for three days, and the estrous cycle is 21–26 days long. In some areas distinct breeding seasons exist. In southern Africa, females have been seen giving birth from August to October, and are joined by the males from late October to January. In
Zambia calves are born in July and August. A Senegalese study focused on the
suckling behaviour of giant eland and common eland calves about one to five months old determined that suckling bouts increased with the age of the calves. No other change occurred in the farmed common eland calves, but in the giant eland calves, the males were found to suckle more than female ones and shorter suckling bouts were marked in
primiparous mothers than multiparous ones. The results suggest that Derby elands that lived in their natural habitat adjusted their maternal behaviour so as to be able to readily maintain a vigilant lookout for predators and other similar risks. In contrast, the farmed common elands behaved as in the conditions of captivity, without predators. ==Populations==