Social network of white rhinos

White rhinos have poor vision. They rely on other senses, first of all, on the sense of smell. And, like many mammals, manure, which they leave in certain places, where everyone can come and smell, is used as odorous tags.

White rhinos Ceratotherium Simum are territorial animals. An adult male occupies a plot of about 11.6 km2, with which areas of several females are overlapped. The territory that the male fiercely protects is significantly smaller - about 1.65 km2. The site contains up to 30 or more Latrin (toilets) located near borders, paths and waterworks. Border heaps are usually used to mark the territory, and males - owners of plots should be left to leave them. However, not only territorial males come to these heaps, but also females, as well as rhinos who do not have their own site. They are divided into two categories: some live here, but do not have rights, others pass by, collecting information about the site, its owner and females and wondering if the owner of the territory is possible. These features of behavior are well known, because the Latrines of white rhinos have long become an object of observation. Back in 1973, they were described in detail by the American biologist Norman Owen-Smith (Norman Owen-Smith), and his work is still referred to [1].

If so many different animals are visited by a manure, then it is obviously not a border post, but a social place that serves to exchange information between rhinos of different sexes and social status. This is not entirely usually, because other types of mammals using Latrines for social contacts have them in the center of their site, and not on the periphery. In short, the features of visiting dung heaps accepted in white rhinos require further study.

Researchers from South Africa and Germany under the leadership of Adrian Schrader took up this task. They worked in the Hluhluwe-Imfolozi Park reserve in the province of Kvasulu-Nanal (South Africa) in the territory of 896 km2. First of all, scientists became interested in what kind of information can be obtained, sniffing manure [2].

Having collected the samples left by different animals, scientists determined the composition of their volatile substances and found that the 2.3-dimetilundecan allows us to judge which floor the rhino, heptanal-about age, indicates the territorial status of a male, and 2.6-dimetilundecans-about the estrus of the female. To confirm their conclusions, the researchers synthesized the corresponding odorous marks, saturated the balls of dry grass with them and put these tricks in dung heaps. Having discovered false manure, the territorial males reacted violently. They perceived the artificial label of an adult male as a threat, more often visited Latrine with this smell, demonstrated aggression, and sensing the female in the state of estrus (preceding mating), tried to find it.

Then the researchers clarified the rules for using the nasopharyngeal information. They were interested in whether all individuals have the right to be noted in these centers or mainly owners of the site, and the destiny of the rest - sniff someone else's manure? Scientists put the video cameras in ten dung wagons and for several months recorded the visits of the rhinos. They managed to collect 2403 records of 233 rhinos, including 115 adult animals. Adult behavior is of greatest interest.

More often than others, the owners of the territory visited the heaps, in second place - subordinate males, behind them by a large margin - past the passing potential competitors and, finally, adult females. They all leave manure there.

As researchers expected, territorial males have a predominant right to leave tags, they do this several times more often than other rhinos, possibly to confirm the status. Even Norman Owen Smith observed that some males are celebrated daily in all heaps. Manure, by the way, is a limited resource. In order to be able to leave odorous marks more often, territorial males must save it and highlight it in smaller portions, which they do.

Both males and females collect information in Latrines. Everyone is interested in their own. The owners of the site sniff the manure more actively more than others, and they show the greatest interest to their own marks. Perhaps the rhinos check whether the smell is weakened.

Adult females and subordinate males read information much less often. Of course, they all pay attention to the marks of the owner of the territory. At the same time, subordinate males also explore the manure of females, seeking the opportunity to somehow hide with them. Females are interested in the smell of not only the Lord, but also other males, as well as females. What the females attract them, the researchers have not yet figured out. Plots of females overlap, so they do not need to mark the territory. Because of the males, they do not compete, because rhino does not show their father’s feelings, and there is no help in raising offspring from them. Researchers believe that attention to the marks of other females is explained simply by the desire to keep abreast of the lives of the neighbors.

It would not be easy to figure out rhinos in all this if the manure was really dumped into a heap, especially since up to 16 individuals are facilitated on one site. Fortunately, this place is structured. The diameter of the site reaches 30 m, and even such large animals as rhinos can observe a certain order. Territorial males empty the intestines only in the center of the heap. Subordinated males also try to get to the center, hoping to declare themselves in this way, 65% of them succeed. However, the owners of the site do not approve of such behavior. They usually have to scatter their manure with its hind legs throughout the site. If the territorial male discovers in the center of the site excrement of another male, he bursts out the manure with special fury, and then visits this heap up to three times a day just like that, check. The researchers did not observe clashes between animals.

Males who do not have their own territory leave tags mainly along the edges of the heap, females, too, are easier to notice them there.

Thus, the location of the mark gives additional information about who left it and facilitates the decoding. Each dung pile is a storehouse of information, and the heap system is the main communicative network of a white rhino.

Natalia Reznik

1. OWEN-SMITH N. Behavioral Ecology of the White Rhinoceros (Phd thesis), 1973, Madison, Wi: The University of WisConsin.

2. Marneweck C., Jürgens A., Shrader am the Role of Middens Inwhite Rhino Olfactory Communication // Animal Behaviur, 2018, 140, 7e18, Doi 10.1016/J.ANBEHAV 2018.04.001.

3. Marneweck C., Jürgens A., Shrader am Dung Odours Signal SEX, Age, Territorial and Oestrous state in White Rhinos // ProC. R. SOC. B, 2017, 284, 20162376, DOI: 10.1098/RSPB 2016.2376.