Social Organization |
Eland can usually be sub-divided into three different social groups. The first is the male group which is the smallest, the female only group, and then the nursery groups that contain females with offspring, young calves, older calves, and not yet mature adults (Moss 1982). There is also another group called a juvenile group, but these are almost always temporary as they will move to either a female group or a nursery group (Moss 1982). Group size, as would be thought, is largest during the wet season when the eland will congregate on the plains to feed on the grasses (Hillman 1987). The male groups are the most sedentary of all of the others, tending to stick around a particular food and water source more so than the female or nursery groups (Moss 1982). The males especially become more sedentary in the later stages of their lives to the point where it is almost predictable to where they will be (Moss 1982). Male groups are also not very stable and males frequently move in and out of many different groups (Hillman 1987). The female groups are much larger and will move over much greater areas, some measured up to 600 sq. miles (Moss 1982). While eland will travel in almost any sort of habitat, the female groups tended to prefer the plains when the rains permit there to be enough grass to eat (Moss 1982). Otherwise, they will move back into the bushier areas to browse (Moss 1982). Female eland are more likely than males to have longer associations with one group; however, the size of female groups can change very dramatically during anytime of the year (Hillman 1987). In a study that was done in captivity it was found that female eland have a complex hierarchy that is mostly linear, an there are many instances of reversals of the rank within the female eland (Wirtu et al. 2004). The subordinate females were those that submidted to the more dominant female as well as those that tended to avoid the dominant female (Wirtu et al. 2004). While the dominant female did display aggressive behaviors toward the subordinates, there was no suggestion that the dominant female suppressed the subordinates in food intake or otherwise (Wirtu et al. 2004). There seemed to be no correlation in body weight to dominance and it is thought that it is the female's mother which gives certain female's dominance (Wirtu et al. 2004). Nursery groups form right after females have given birth to their young (Moss 1982). After a female has given birth it is usually no more than 24 hours until they are both within a nursery group (Moss 1982). Soon after the mother and calf join the nursery group, the calf forms bonds with other calves that appear to be even stronger than the bond between the mother and the calf (Moss 1982). During the rainy season, when the herds are in the grasslands, the nursery heards can get very large and even when the mother leaves the nursery herd the calf stays behind due to its bond with the other calves (Moss 1982). Eventually, the nursery groups begin to break up when the juveniles reach the age of 2, and go and join female and male groups (Moss 1982). |