Thailand has, for the first time, administered contraceptive vaccines to female wild elephants, as part of an initiative to control the elephant population safely and promote sustainable coexistence between humans and elephants.
The Department of National Parks, Wildlife and Plant Conservation carried out the operation on three female wild elephants in Bo Rai district, Trat province, on January 25th.
The vaccination program is the result of cooperation between the department’s Wildlife Conservation Office and Chiang Mai University.
Sukhee Boonsang, director of the office, revealed that the project was initiated due to the rapid growth in the wild elephant population in eastern forest areas. Their numbers increased from 334 in 2015 to 799 in 2025, an annual growth rate of approximately 8.2%.
As a result, elephants have increasingly been venturing into community areas in search of food, as forest resources and living space have become insufficient.
Since 2012, this situation has led to 141 human fatalities, 170 injuries and agricultural damage across more than 100 sub-districts in six provinces.
The vaccine used is a contraceptive specifically designed for female wild elephants.
It involves neither sterilisation nor surgery. Instead, it works by stimulating the immune system to prevent fertilisation of the egg. The vaccine can prevent pregnancy for up to seven years. After that, if no booster is administered, the elephant naturally regains the ability to breed.
According to Sukhee, the vaccine has already been tested on African elephants, as well as seven captive elephants in Thailand, and has been found to be 100% safe, with no side effects. The vaccinated elephants continue to live healthy and normal lives.
Veterinarians and officials vaccinated three adult female wild elephants from a herd of twelve in the Khlong Kaew Waterfall National Park area.
The mission began at 9pm and involved delivering the vaccine via dart gun without anesthesia, ensuring maximum safety for both the elephants and the staff. The operation concluded at 10pm.
The team will closely monitor the elephants for 48 hours and plans to collect blood and fecal samples every six to eight months over the next seven years to assess immune response levels.
The project stems from concern for the welfare of wild elephants. If the population exceeds the forest’s capacity, elephants may face food and water shortages, as well as increased risk of road accidents, electrocution and conflicts with local communities.
Using a safe contraceptive vaccine is therefore an approach that improves the elephants’ quality of life, ensures sufficient natural resources and reduces the risks associated with human-elephant encounters, ultimately leading to truly sustainable coexistence.
