Disturbance from humans altering behaviour of rhinos in Kaziranga: Study
The researchers carried out the study from 2016 to 2018 to collected 179 samples of disturbance distance and 5,091 samples of behavioural data of the rhinos
Disturbance caused by human interference including those by tourists is altering the behaviour of the one-horned rhinos in Assam’s Kaziranga National Park and Tiger Reserve (KNPTR), a new study revealed.
KNPTR is the largest habitat of the species listed as vulnerable by IUCN (International Union for Conservation of Nature).
According to a 2022 census, KNPTR houses 2,613 one-horned rhinos.
Between October last year till mid-May this year (the tourist season when the park remains open), 443,636 tourists visited KNPTR making it the third most visited wildlife destination in the country. There has been a four-fold increase in the number of tourists to the national park in the past 10 years.
“Indian rhinoceros are significantly affected by the disturbance of human interference. In the present study, changes in the normal behaviour were observed in the presence of intruders. The usual behaviour altered into alertness, flushing or chasing as a response to the stimuli,” the study carried in the latest edition of Nature, a British scientific journal, published last week, stated.
The researchers, Sangita Medhi of the zoology department of Guwahati-based Suren Das College and Malabika Kakati Saikia of Gauhati University’s zoology department carried out the study from 2016 to 2018 to collected 179 samples of disturbance distance and 5,091 samples of behavioural data of the rhinos.
“The study proves that the behaviour of rhinos in KNPTR is changing due to disturbance by human interference. It would help the animals and also protect viewers if these factors are taken into account when tourists visit the national park,” Malabika Kakati Saikia, one of the authors of the study, told HT.
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Disturbance distance is the distance at which an animal (or bird) feels disturbed due to some unusual external factors like presence of intruders of humans that leads to changes in their normal behaviour and activity. In this study, the rhinos showed three types of behavioural changes due to external factors.
One was alert behaviour, when rhinos stopped their normal activities in the presence of external factors and tried to identify the source of the disturbance.The second was flushing behaviour, when the animal flees from the spot when they detect some unusual external factors. The third is chase behaviour when the rhinos tried to chase away the source of disturbance.
“Wind direction was a factor influencing the disturbance distance. The eye sight of rhinos is poor but the sense of smell is very prominent and the speed of wind is higher during the winter season. Hence, the wind had an effect on the rhinos on feeling the presence of an intruder,” the study, which HT has seen, read.
“These behavioral changes occurred at varying distances, with alertness being observed at the highest distance, followed by flushing and then chasing. The alert distance can be considered as the tolerance limit of rhinoceros against human disturbances. However, flushing and chasing behaviour indicates a higher level of disturbance which is intolerable and defensive,” it added.
The study found that the distance of disturbance varied between tourist and non-tourist areas. It was found to be lower in tourist areas and higher in non-tourist areas. This is likely due to the impact of human interference, indicating higher disturbance levels in tourist areas.
“However, the animals in the non-tourist area become alert at a longer distance compared to animals in the tourist area. In non-tourist areas having less disturbance by human interference, the animals can detect the stimuli from a longer distance,” the study said.
It found that the behavioural response of the rhinos varied among different age and sex groups.
Lower alert distance and higher flushing distance in females and calves indicates that rather than flushing away the females try to examine the problem as females were mostly found with calves. It noted higher alert distance and lower flushing distance in males.
“The disturbance distance was found to be higher in short grassland and lower in woodland which prevails that animals at a longer distance in the short grassland shows reaction towards the intruder. Whereas, in woodland it decreases with the decrease in the visibility due to dense canopy. However, in tall grassland it was found moderate,” it said.
These changes are enhanced by the visibility of the source of disturbance. Availability of higher vegetation cover and consequently lower perceived risk of predation increases the tolerance distance, it added.
Another factor that affected disturbance distance was the direction of the wind. The disturbance distance was found to be lowest when the wind direction was from observer to animal. Moreover, the disturbance distance is less when there is no wind.
“The Indian rhinoceros has a strong sense of smell and power of hearing. The wind helps to spread the smell of the observer (human intruder) and when there is no wind, they can detect the sound more quickly. These are most likely the possible reasons for the above observation,” the study said.
The study concluded that there are different behavioural responses against the disturbance found in one-horned rhinos in KNPTR. The disturbance distance is influenced by the habitat structure, age and sex group, wind direction, among others.
“However, there are many other factors which may affect the disturbance distance like, the intruder’s behaviour, its clothing, type of riding source, speed of the vehicle etc. and hence needs more intense study,” it stated.
It suggested a limit of in approach distance in the park and implement some law for the vehicle drivers to maintain the behaviour of the peoples. Providing drivers of safari vehicles with education on behaviour of rhinos due to different disturbances could help them control tourists, it noted. It suggested that a minimum distance of 100-200 metres should be maintained between the animals and the viewers.
