Spot-billed pelicans are set to arrive for nesting in Kokkarebellur Community Reserve in the Maddur taluk of Mandya beginning October, but forest officials and bird lovers are on the edge due to the deaths of about 100 pelicans reported in the last four years. Though the primary cause of the deaths of the pelicans is yet to be determined, lab tests and studies are underway to find the source.

A few years ago, these birds used to arrive in December. In the last couple of years, spot-billed pelicans began arriving in Kokkarebellur, which is famous for sightings of the bird, at the end of October. These birds typically start to breed from December and stay in the region till June/July with their offspring. However, the period from December to February/March is vulnerable for these birds as the majority of deaths were reported in these months. As many as 59 died in the 2017-2018 season, 17 in the 2018-2019 season and 12 in the 2019-2020 season.

Aksheeta Mahapatra, a wildlife researcher from the Wildlife Institute of India, Dehradun, is working with the Karnataka Forest Department to study the cause of these deaths. She noted that lab tests and necropsy have revealed that a roundworm infestation may have led to the spot-billed pelicans’ deaths. However, while these worms are commonly found in living beings, they are not usually lethal.

Spot-billed pelicans infested by worms treated at Kokkarebellur

To that end, Aksheeta notes that the roundworm infestation is likely the secondary cause of the deaths, while the primary cause of deaths is still not known. “There is something else that is triggering their immune system and making it weak, and as a result, the roundworms are multiplying. Infested birds are unable to eat and drink anything and die after falling from trees,” she said.

What has baffled forest officials and researchers is that spot-billed pelicans also nest in other parts of Karnataka, Andhra Pradesh and Tamil Nadu, but the deaths have been centred in Kokkarebellur. There have also been some deaths reported in Kukkarahalli and Lingambudhi lakes in Mysuru city. In Kokkarebellur, herons, egrets and painted storks are among the other birds that share space with spot-billed pelicans, but deaths have been reported only in pelicans.

Contaminated water bodies in the vicinity of Kokkarebellur, particularly in River Shimsha, a tributary of the Cauvery, flowing half a kilometre from the community reserve, is said to be one of the causes for the pelican deaths. Villagers allege that untreated sewage from Maddur and Shivapura as well as from nearby sugar factories are also discharged into the water bodies.

Untreated sewage water and industrial effluents have contaminated River Shimsa

A forest staffer explained that spot-billed pelicans gulp some amount of water while catching fish in the water bodies. As contaminated water enters their stomachs, they could get worm infestations. However, another staffer said that pelicans leave Kokkarebellur after July and return only in October, leading to the theory that the birds may be contracting the infestation elsewhere before coming to Kokkarebellur and succumbing to illness.

Ardent bird lover Linge Gowda, a well-known face in Kokkarebellur, has rescued hundreds of chicks that fall from nests either due to sibling competition, strong winds or other reasons. Chicks have been raised at the rescue centre since 1994.

But Linge Gowda is now concerned at the mass deaths around the adult birds, something he has not witnessed in his lifetime. He is also worried about the fact that the deaths have all occurred in the last four years.

The number of spot-billed pelicans visiting Kokkarebellur has decreased as well. A source monitoring the number of birds said that earlier about 500 to 600 pairs of birds used to arrive to nest, but in the last couple of years only about 250 pairs arrived for nesting. However, the number of painted storks has remained the same, with the reserve reporting about 1,000 pairs each year.

Linge Gowda pointed out that the number of trees for pelicans to nest has dwindled in recent years as well. It has been one of the main reasons that the pelicans are not coming in the numbers that they used to years ago, he said.

Forest officials, however, remain hopeful and say that the number of deaths of the spot-billed pelicans have fallen significantly in the last two years. They have also begun to plant saplings in the reserve.

Lokesh, a staffer at the Forest Department posted at Kokkarebellur, said two pelicans were rescued during the early stages of infestation this year. After treatment, both recovered, one in January and the other in September. If the infection is found early, it improves the chance of recovery, he said. That has often not been the case because they only learn about a bird’s sickness when it falls from the trees, and it is too late at that point.

A spot-billed pelican rescued in Kokkarebellur after falling from a tree

Satish, a veterinarian who has conducted necropsy on the carcasses of the pelicans, said that it is impossible to disinfect the water bodies in surrounding villages since some of them are huge. He hoped that the pelicans would develop resistance to worm infestation naturally instead.

Deputy Conservator of Forests, Mysuru Wildlife Division, Alexander said though preventive measures are low, the Forest Department is working to minimise the deaths. Among the steps being initiated, Alexander explained, fishlings have been added to nearby tanks so that pelicans can feed in close proximity and avoid contaminated water bodies.

Girisha is a freelancer who writes on wildlife and the environment.