2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
British biologists have proposed scaring rhinos from places where they are likely to become prey for poachers, according to Proceedings of the Royal Society B. Scientists have tested several ways to scare off rhinos: the sounds of a siren, drones flying at different heights and the smell of hot red pepper. It turned out that pepper acts on animals rather as an attractant, and the siren and the sound of a drone flying at a low altitude make them run away.
The population of southern white rhinos (Ceratotherium simum simum), living in South Africa, numbers about 20 thousand individuals. Researchers estimate that in 1900 the number of white rhinos did not exceed 50, so conservation biologists consider the restoration of the population a great success. However, poachers do not leave rhinos alone: their horn is used in traditional Chinese medicine and is in great demand in the countries of East and Southeast Asia. Therefore, despite the fact that animals live in protected areas, poachers kill about a thousand rhinos per year. In 2010–2016, more than 6, 5 thousand animals were killed by poachers.
However, the risk of encountering poachers for rhinos is not the same everywhere. It depends on the distance to the nearest fresh water source, the presence of nearby buildings or roads, the number of animals living in the area and its topography. Poachers prefer to hunt at dusk or at night, preferably in the moonlight. They also take advantage of the bad weather to evade the reserve patrols.
A good defense for the rhinos would be to stay away from the most popular poachers. Such a strategy would work for private nature parks. They are fenced in and smaller than national parks, but they are home to only about 30 percent of the rhino population. One possible solution is to scare rhinos away from popular hunting spots for poachers - similar animal protection devices already exist. Studies have shown that the buzzing of African bees effectively scares away elephants, and monkeys, bears and the same elephants cannot stand the smell of capsaicin, an active component of red hot pepper.
Samuel Penny of the University of Brighton and his colleagues suggested that rhinoceroses could also be deterred by the smell of hot red peppers, the sound of a siren, or a disturbed hive. The authors also decided to check how rhinos will react to the sound of drones flying at an altitude of 20, 60 and 100 meters. The researchers suggested that the animals would flee from drones flying at low and medium altitudes, but would not pay attention to sounds coming from a height of 100 meters.
Scientists conducted experiments from October 2016 to November 2017 in a private nature park with an area of 47 square kilometers, located in the Northwestern province of South Africa. In acoustic experiments, 12 rhinoceroses were allowed to listen to a repeated ascending siren howl, the buzzing of bees, or, as a control, the cry of a South African turtle dove. Each sound lasted one minute and was turned on by the animals up to four times. The speaker was at a distance of 50-150 meters. Drone experiments were also carried out on 12 rhinos. In 150 meters from them, the researchers launched drones at different heights. In order to test the reaction of rhinoceroses to odors, 17 individuals were allowed to sniff ropes, which were previously dipped in sunflower or pepper oil.
The siren turned out to be the most powerful stimulus among the sounds. Hearing it, the animals ran away, on average, 46 meters (p <0.001), and hearing the buzzing of bees and the cry of a turtle dove, they remained in place. From drones flying at an altitude of 20 meters, rhinos ran the farthest, on average 61 meters (p = 0.003). Drones flying at high altitudes frightened them much less, having heard the sound, the animals, on average, ran away 10 meters (p = 0.003). From drones flying at an altitude of 60 meters, rhinos, on average, ran 20 meters away (p = 0.007). But the smells did not make an impression on the rhinos. Moreover, the smell of hot pepper acted on them as an attractant: they began to chew on both ropes soaked in both pepper and sunflower oil.
According to the authors of the study, a drone flying at a low altitude turned out to be a more effective means of controlling the movement of rhinos than a siren - it is able to chase animals and has a longer signal transmission range. “The ability to control the drone also allows for more precise control of the movement of the rhinoceros, as the drone can move in response to the rhino's change in direction of movement. In fact, drones can be used to herd them,”says Samuel Penny.
Earlier, the South African authorities calculated that in the first eight months of 2018, the number of rhinos killed in the country fell by a quarter, despite the increase in poaching activity.