Kigali: Human presence may negatively affect mountain gorillas potentially lowering immunity and increasing the likelihood of the precious primates acquiring human-borne diseases, according to British researchers.

The team says uncontrolled constant contact with humans makes the gorillas aggressive. Based on observation of the silverbacks, the study says 39% aggressive events were human directed in the case of adult females.

The study came before the premier gorilla-naming event ‘Kwita Izina’ on June 05 where up to 14 baby gorillas were given names. The event also coincided with the World Environment Day – celebrated in northern Rwanda.

The study titled the “Behavioral responses of one western lowland gorilla (Gorilla gorilla gorilla) group at Bai Hokou, Central African Republic, to tourists, researchers and trackers” is published by the American Journal of Primatology. The research was done over a 12 month period. 

The study recommends expansion of the human viewing distance from the current 7 meters to a more than 18 meters, and for tourist visitors to be compelled to wear face masks to prevent transmission of communicable diseases to the animals.

“Close observer-silverback distance correlated with a decrease … feeding rates and an increase in human monitoring,” reads the study in part, conducted by behavioral researcher from the University of Stirling and University College London. 

“We recommend increasing minimum observation distance to [greater than] 10m where possible, decreasing observer group sizes, particularly after a visit consisting of maximum numbers and restricting tourist access to 1 visit [per] day,” say the researchers.

Rwanda earns most of its tourism revenue from gorilla-related tourism with tens of thousands coming into the country. The authorities have set aside massive resources monitoring the habituated groups open for visits by tourists, collecting added data from groups set aside for research, and from encounters by their wardens, rangers, and trackers with groups not habituated at all.

Mountain gorillas are found in their natural habitat shared between Rwanda, the Congo DR, and Uganda across the Virunga mountain range. The animals are said to live under close supervision and around-the-clock protection by rangers and trackers.

The current standards set up by the three countries require regular visits in close range by as many as 8 tourists. However, the British researchers say such numbers are large and are impacting on the social behavior of the mountain gorillas.

Rwanda expects to attract 750,000 tourists this year, generating $44.4 million which can be put towards protecting gorilla, according to available figures.

Uganda is said to record the largest number of mountain gorillas in the two national parks of Bwindi and Mgahinga, with Rwanda a close second in terms of numbers found in the Parc de Volcanoes, while surveillance and counts in Congo DR have of late been stepped up to ascertain the exact number of the gorilla groups and their respective family members found there.