Why are juvenile elephants dying in Kerala?

Using the block-count method, the survey has estimated the state’s elephant population to be 1,793 in 2024, a decline of roughly seven per cent over the previous year. 845 elephants have died across the state’s forests and elephant reserves between 2015 and 2023, with the death rate increasing over time.

While the death rate in elephants has declined with the increase in age, juvenile elephants (aged ten and below) are particularly susceptible to the Elephant Endotheliotropic Herpesviruses (EEHVs), with a 40% death rate reported.

What are EEHVs?

EEHVs are a class of novel double-stranded DNA herpesviruses which cause acute haemorrhaging in juvenile Asian and African elephants, with severe cases causing death within 24 hours of infection. Given the endangered status of the Asian elephant, EEHVs pose a dire threat to conservation efforts. The disease itself has coexisted with elephants for millions of years, however, young elephants are particularly vulnerable on account of the lower EEHV-specific antibody levels compared to the seniors.

Calves in large herds of elephants benefit from shared immunity through exposure to different EEHV strains, enabling them to develop the antibodies to fight the virus effectively. The smaller size of herds in Kerala thus presents a crucial challenge, with the majority of elephant sightings – 56 per cent – being reported as individuals and pairs. Clans of over ten individuals are extremely rare and constitute one per cent of all documented elephant sightings.

Why are elephant herds smaller?

According to the report, the size of a herd depends on the quality of its habitat, with larger herds with calves favouring locations with an adequate mix of grassland, forests and water sources.

The decline in forest cover and sub-optimal elephant habitats are partly responsible for the smaller herd sizes. The report cites ‘biological invasions,’ mainly the cultivation of alien species of plants like acacia mangium and eucalyptus in forest tracts as a major reason. The lack of fodder could lead the herbivores to farmlands located around the forest areas, increasing the scope of human-elephant conflict. The smaller herd size could also lead to changes in an individual elephant’s behaviour.

Resolving the problem of shrinking habitats and restoring them to their natural state, free of alien species, is imperative to reducing the threat of EEHVs to Asian elephant calves, as well as avoiding further fragmentation of elephant herds.