The Impala Rut

Author: Ryan Johnston

When we speak of the word “rut” we are referring to the breeding time of different antelope and deer species around the world. As we reach the end of May, beginning of June, we approach the end of the impala rutting time. For the past six weeks or so, rams have been acting like absolute lunatics, chasing one another around and setting up harems (groups of females). In this time, they try and breed with as many females as they can. Males throw all caution to the wind at this time and it may cost them dearly or prove to work out in their favour massively.

Timing

The rutting season for impalas typically occurs during the late autumn to early winter months in Southern Africa. This is right at the end of the rain season and animals are in peek physical condition. Once the females start releasing their pheromones, the males kick into gear.

In East Africa, this is a little bit different and females seem to come into oestrous throughout the years at different times. This means males are continuously competing for harems, although not quite as intensely as they do further south. Males are generally also larger, with beautiful horns as they have a more constant flow of higher testosterone levels through the body.

Behaviour

Impala are generally not territorial as rule of thumb, but rather live in home ranges. During the year, middens are used by both sexes to advertise presence. It is almost like a newspaper that other impala can come and “read’, figuring out who else is around. Rams will be far more active at these during the rut. During this time though, male impalas do stick to areas and become more territorial. Areas that will attract harems of female are obviously more favoured as the females themselves prefer these areas for obvious reason. The size of these territories can vary based on the density of the population and the availability of resources.

Rams engage in various displays to assert dominance and attract females, including loud grunting calls (which people often confuse for lions if it’s their first time hearing it), neck stretches, and horn displays. Horning bushes and trees can often be seen and it is said to show of the strength of the ram and what he is capable of doing to a rival. All of these behaviours and displays serve both to intimidate rival males and to impress females.

Male impalas may engage in physical confrontations, which can include chasing and head-to-head clashes with their horns. These fights help establish dominance hierarchies, determining which males are most successful in mating. It can be quite comical watching to rams sizing one another up, as they circle one another and practice lip licking while doing so, circling one another at the same time.

Mating

Once a ram has become dominant and has his harem in check, he will breed with any of the females that is in oestrous and is receptive. The male will closely follow her, and copulation occurs multiple times over a short period. Copulation itself is short as it is awkward and also a dangerous time. Not all of the females will be receptive at exactly the same time. What this means is that a single male, won’t breed with all of the females, but will rather rotate.

Males generally only hold onto a harem for three to five days before they are ousted by another male. While with their harems, the males do not eat or drink as much as they should. They are too busy keeping the ladies together, advertising dominance, fighting and chasing other males. This means that a ram that they would easily chase off in day one and two, make beat them later on. In this way, numerous males will mate with a harem and so is a good way of keeping the gene pool clean and more diverse.

Predation and death during the rut

Studies in previous years have shown that a fare amount of rams die during the rutting period. Whilst the males are driven mad by the pheromones that are released by the females, they do not pay enough attention to their own health and well being. Rams occasionally kill one another whilst fighting or drive themselves to death through sheer exhaustion.

Predators also take advantage of this as the rams minds are elsewhere. The big cats will even change their hunting strategies during this time. They will often just rest and listen, waiting to hear the guttural call of the rams or the clashing of horns. If they hear this, they are off as they know the males are not paying attention and can be picked off more easily. It is thought that 95% of prey deaths in May – June, is impala rams.

Gestation period and lambing

Female impalas have a gestation period of about six to seven months. They typically give birth to a single calf in the summer months, which coincides with the rainy season when food resources are more abundant. It is an old myth that they can hold their lambs back until the first rains and only give birth then. 

As the females are all bred with within a close period, the lambs are all born very close together. This is one of the strategies of impala, flooding the predatory market, survival through sheer numbers. Although they have many predators, cats, hyenas, jackals, even large birds of prey and snakes, because of the sheer number, a lot of the youngsters survive.

Conclusion

As the most numerous of Africas antelope May and June can be a very entertaining time of year in Southern Africa. From fighting, to mating impala, through to busy and curious predators. It may seem sad that a lot of these males are picked off, but it all has a purpose. With the success of this time, later on in the year is more plentiful for all. From viewing cute impala lambs to predators benefiting and raising their own young.

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