| Tsessebe | |
|---|---|
| Tsessebe in Botswana | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Family: | Bovidae |
| Subfamily: | Alcelaphinae |
| Genus: | Damaliscus |
| Species: | lunatus |
| Subspecies: | lunatus |
| Binomial name | |
| Damaliscus lunatus lunatus [2] |
|
The Tsessebe (Damaliscus lunatus lunatus), is one of five subspecies in Damaliscus lunatus. The other subspecies include Korrigum (Damaliscus lunatus korrigum), Tiang (Damaliscus lunatus tiang), Coastal Topi (Damaliscus lunatus topi), and Topi (Damaliscus lunatus jimela). Tesessebe are found primarily in Zambia, Namibia, Botswana, Zimbabwe, and South Africa.[2] They used to be spread throughout a significant amount of Africa, from Senegal to eastern Ethiopia down to the northern areas of South Africa.[3] Tsessebe belong to the same family as springboks and wildebeest (Bovidae) and can run at a maximum of 60 kilometers per hour.[4]
Contents |
Adult Tsessebe can be anywhere between 150 cm and 230 cm in height.[5] They are quite large animals with males weighing 137 kg and females weighing 120 kg on average.[6] Their horns are anywhere from 37 cm for females to 40 cm for males. For male Tsessebes horn size plays an important role in territory defense and mate attraction although horn size is not positively correlated with territorial factors of mate selection.[6] Their body's are chestnut-brown. The front of their face and tail tuft are black, the forelimbs and thigh are greyish or bluish-black. Their hindlimbs are brownish-yellow to yellow and their belly's are white.[7] In the wild Tsessebe usually live to become a maximum of fifteen years of age. However, in some areas their average life-span is drastically decreased due to over-hunting and the destruction of habitat.[7]
Tsessebe are social animals. Females form herds composed of six to ten cows with their young. After males turn one year of age they are ejected from the herd and form bachelor herds that can be as large as thirty young bulls. Territorial adult bulls form herds the same size as young bulls although the formation of adult bull herds is mainly seen in the formation of a lek[4] Tsessebe declare their territory through a variety of behaviors. Territorial behavior includes moving in erect posture, high-stepping, defecating in a crouch stance, ground-horning, mudpacking, shoulder-wiping, and grunting. The most important aggressive display of territorial dominance is in the horning of the ground. Another far more curious form of territory marking is through the anointing of their foreheads and horns with secretions from glands near their eyes. Tsessebe accomplish this by inserting grass stems into their pre-orbital glands to coat it with secretion, then waving it around, letting the secretions fall onto their heads and horns. This process is not as commonly seen as ground-horning nor is its purpose as well known.[8]
There are several behaviors that strike scientists as peculiar. One such behavior is the habit of sleeping Tsessebe to rest their heads mouth down on the ground with their horns sticking straight up into the air. Male Tsessebe have also been observed standing in parallel ranks with their eyes closed bobbing their heads back and forth. These habits are peculiar because scientists have yet to find a proper explanation for their purposes or function [8]
Tsessebe are herbivores that primarily graze [9] in grasslands, open plains, and lightly wooded savannahs. But they are also found in rolling updlands and very rarely in flat plains below 1500 m.[8] Tsessebe found in the Serengeti usually feed in the morning between 8:00 a.m. to 9:00 a.m. and in the afternoon after 4:00 p.m. The periods before and after feeding are spent resting and digesting or watering during dry seasons. Tsessebe can travel up to 5 kilometers to reach a viable water source. In order to avoid encounters with territorial males or females Tsessebe usually travel along territorial borders even though it leaves them open to attacks by lions and leopards.[8]
Tsessebe reproduce at a rate of one calf per year per mating couple.[5] Once a calf is born they reach sexual maturity in two to three and half yearsTsessebe. After mating the gestation period of a Tsessebe cow lasts seven months. The rut, or period where females are receptive to mating, starts in mid-February and stretches through March.[4]
The breeding process starts with the development of a Lek. Leks are established by the congregation of adult males in an area to which females visit only for the purpose of mating. Lekking is of particular interest since female choice of a mate in the lek area is independent of any direct male influence. There are several options available to explain how females choose a mate, but the most interesting is in the way that males group in the middle of a lek. The grouping of males can appeal to females for several reasons. First, groups of males can provide protection from predators. Second, if males group in an area with a low food supply it prevents competition between males and females for resources. Finally, the grouping of males provides females a wider variety of mates to choose from seeing as they are all located in one central area.[10] Dominant males occupy the center of the leks and so females are more likely to mate at the center than at the periphery of the lek[9]
A study by Bro-Jorgensen (2003) allowed a closer look into lek dynamics. As was said previously, the closer a male is to the center of the lek the greater his mating success rate. In order for a male to reach the center of the lek he must be strong enough to out-compete other males. Once a males territory is established in the middle of the lek it is maintained for quite a while and even if an area opens up at the center males rarely move to fill it unless they are able to out-compete the large males already present. However, maintaining central lek territory has many physical drawbacks. For example, males are often wounded in the process of defending their territory from hyenas and other males.[11]
The population of Damaliscus lunatus was estimated to be in the tens of thousands in 1998 and thus declared at low risk of extinction. However, the IUCN Species Survival Commission observed a general population decline that would result in the population becoming vulnerable to extinction by the year 2025.[2] As was mentioned earlier, Tsessebe populations were present in much greater numbers but populations declined due to habitat destruction with bush encroachment playing a primary role.[3]
Damaliscus lunatus, The Ultimate Ungulate Factsheet