Patterns of Social Organization and Social Spacing

Definition: "The modal grouping pattern of a species"(Berger, Joel and Stevens, Elizabeth F.1996).

Dikdiks live on classical territories in family groups composed of one adult male, one adult female, and one or two offspring. A classical territory means that all the necessary resources like food, space, and good nesting sites are found in one well-defined place. Territories, ranging from six to thirty acres, are defended mostly by the male. Females have been known to initiate threat displays to other dikdiks and even inform their mates of in intruder. The most common form of mutual defense is the dunging ceremony. During this ritual, the perimeter of the territory is marked with dung middens and urine. Dung middens are very high piles of feces approximately thirty centimeters in diameter. Dung middens of neighboring families are very close together, but never touch. Each dikdik is aware of and respects the boundaries of the opposite group. The female initiates the ceremony by urinating and defecating over the pile with the male following behind her repeating the process. He drops his feces directly on top of the females as a form of scent marking. Males cover up the females scent in order to keep other males away. (If other males smell the female, they might test the dominance of her mate and try to steal her!). Both partners end the ceremony by marking nearby leaves and bushes wiith secretions from their preorbital glands.

Other defense mechanisms include alarm signaling, dominance displays, and ritualized fighting. When threating other dikdiks, adult males usually hold an erect posture with an erected crest to show his opponent that he is the more dominant one. According to Estes, Salt's dikdiks also stand with their backs hunched and necks drawn in when they prepare for attack (Estes, 1991). If the intruder decides to submit, he usually stretches out on the ground with his head low. He must make sure that his opponent recognizes his surrender by revealing all his weak spots. If the intruder continues to approach the boundaries, the male begins jumping back and forth, but never crosses his own lines. This behavior is similar to a human's bluff when individuals jump at each other, but do not physically attack their opponent. If the competitor refuses to flee, the two dikdiks engage in a ritualized fight. Continuing to test their opponent's RHP, the males run toward each other sometimes jabbing the other with their horns. The confrontation ends with one of the males fleeing or both simply moving farther apart and feeding on nearby shrubs. Another sign of dominance display occurs when the male rips bark from the trunk of the tree with his horns. Males usually become more aggressive toward outside males and his own sons when the female is in oestrus. Petr E. Komers and Peter Brotherton also found that males were usually less aggresive towards intruding females than towards the males. It was the female who defended the territory against single females that might try to steal their mate.

Adult males and females form strong, long-lasting pairs, which exist independently of the territory. Pair bonds are maintained through interactive social behaviors such as playing (between juveniles), social grooming, alarm calling, and the dunging ceremony. Once these pairs are joined, the couple is rarely seen apart, even when feeding or defending the area. Studies show that most males never form new bonds with a neighboring female after their mate dies or they do so after a long 'mourning time'. However, females are quicker to find new mates because neighboring males start pursuing the woman soon after her mate dies. Nonbreeding adults do not belong to the family and subadults are rarely permitted to remain with the mother and father.

THE BIG QUESTION: WHY?

***When considering why the dikdik exhibits these patterns of social organization and spacing, one must understand the ecological conditions surrounding the animal and know what resources are critical for survival. The necessary resources include food, space, good nesting sites, shade, and few competitors.

First of all, dikdik habitats are saturated making it almost impossible for new animals to move in and establish a territory. Therefore, it is critical that adults choose their territory carefully and mark its boundaries so that other dikdiks do not cross over into their land. Also, dikdiks are highly selective browsers feeding on acacia leaves, shrubs and fruits widely dispersed across the area. The predominant feeding times are from dawn until early afternoon and midday until late night. Because these antelopes eat fast and can forage over one area very quickly, it is more advantagous for them to establish territories in small family groups in order to prevent quick depletion of resources. This requires that they be familiar with the area, which is more accessible over a smaller plot of territory. Lastly, defending a smaller territory is more energy efficient and less time consuming for the dikdik. Another reason for traveling in family groups is the high predation pressure. The most common predators are carnivores like eagles, pythons, servals, lions, hyenas, cheetahs, and wild dogs. For the dwarf dikdik, alertness and vigilance is key for its survival. Hiding is one of its main antipredator strategies, which is much easier to do in pairs when the animal is very familiar with the territory. The safety in number principle does not apply to this mammal. Instead, the male dikdik watches and listens for predators, and may even make alarm whistling calls to warn his family of the attack. This whistling call confuses the stalker. Other antipredator tactics include freezing, often with one leg raised, and running. When chasers like the wild dog approach dikdik territory, the dikdik drops to the ground and freezes. No whistling sounds are emitted. The animal jumps up and runs away, darting in and out of bushes. Seconds later, it drops to the ground. Again, we see the importance of knowing the territory thoroughly. Most often, males are on the lookout more frequently than the females. The male is concerned with protecting his family, not other dikdiks in the area. Sometimes other dikdiks might hear the whistling 'zik-zik' call, but the male's intentions are not specifically to warn everybody about the predator. It is the male's responsibiilty in each family to take care of his own mate and young.

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