TEHRAN – Miankaleh international wetland has recently witnessed the death of over 13,000 migratory birds. Although veterinary organization announced that the birds have been killed due to the “botulinum toxin”, some environmentalists believe that water pollution and other factors that have not yet been investigated have caused unprecedented bird mortality in the area.

Miankaleh a long and narrow peninsula is 48 kilometers long, and between 1.3 and 3.2 kilometers wide, which sets apart the Gorgan Bay from the Caspian Sea. Four villages namely Ashuradeh, Qezel-e shomali, Qezel-Mehdi, and Qavasatl are situated on the peninsula. 

The peninsula was designated a Ramsar site in 1975 and called Iran's bird-watching paradise. Major habitats include wetlands, inter-tidal mud with sandy shores, shallow marine waters, forests, peatlands, and agricultural areas. It is home to many unique Caspian birds and reptile species native to this region. It's also a very important internationally-recognized refuge for migratory birds.

Water deficit, mismanagement, unsustainable agricultural practices, and severe depletion of the wells and groundwater resources have exacerbated Miankaleh peninsula’s condition.

Overgrazing, illegal hunting, fishing, deforestation and the unplanned spread of villages are some of the challenges posing threat to the region’s environment.

Lack of scientific information in wildlife veterinary

On January 23, mysterious death of migratory birds in Miankaleh were first reported in the media. Two days later, the Department of Environment (DOE) announced that an expert team was being sent to the area to investigate the cause of death. 

The veterinary organization also said that tests based on avian influenza and Newcastle disease have been ruled out and further investigations are needed to determine the exact cause. 

Three days passed, and the deaths of migratory birds were still in a state of uncertainty, with the death toll increasing day by day. 

Iman Memarian, a wildlife veterinarian, told ISNA on Wednesday that unfortunately we have a lack of knowledge in the field of wildlife veterinary medicine; and taking several days to determine the exact cause of bird death is a proof to the fact.

Another evidence of the lack of wildlife veterinary science in the country is that we raise the issue of Newcastle disease for the purpose of investigating the migratory birds’ death, while aquatic birds are highly resistant to the disease, he said.

Even in zoos, aquatic birds do not need to be vaccinated against Newcastle disease, he lamented.

Anxiety signs observed in bird carcasses

As the number of bird deaths has risen to 10,000 in Miankaleh, experts and NGOs in Mazandaran province claimed that industrial wastewater released into Miankaleh has caused water contamination and could be a cause of death. 

Memarian said that the published footage of bird carcasses showed symptoms of nervousness that could reinforce the theory of heavy metal poisoning, and that feeding manually is very dangerous for migratory birds and could cause food poisoning.

The veterinary organization announced last Tuesday that "botulinum poisoning" was the reason behind mass bird mortality. 

Botulism is caused by a toxin produced by the bacterium Clostridium botulinum, and the birds become infected by the ingestion of plants or animals infected with the toxin and lose their lives. 

Clostridium botulism is an anaerobic bacterium that grows in decaying plants and animal material and often occurs in lakes during periods of lack of oxygen and poor water quality.

Esmaeil Kahrom, an ornithologist, stated that "If we accept the veterinary organization's claim of feeding the birds in a closed and polluted wetland environment, then the question arises whether all the birds at one point, decided to drink water and die together?”

“It is not possible for several thousand birds to drink water and die at once in the wetland where botulinum toxin is, did they commit mass suicide? did birds have symptoms of yellow excrement and yellow liquid outflow from the mouth?”, he lamented.

He further suggested that the death of migratory birds in the wetland might be deliberate and claims that some fishermen, landowners or hunters may have thrown poison into the water and killed these species.

Kahrom said that the birds are a victim of conflict of interest and emphasizes the need to pursue and punish the main contributors to this environmental phenomenon.

Soheil Oladzad, an environmental activist and expert, also said in a report published by the Shahrvand newspaper that "We sent four birds with great difficulty kilometers away from Mazandaran to carry out the necessary tests and investigate the cause of death, but they didn't cooperate under some circumstances. 

Memarian had also previously told ISNA that botulinum toxin bacteria were unlikely to grow extensively in the ponds.

Lack of water flow into the wetland produced botulism

Despite different speculations about the incident, Shahaboddin Montazemi, director of wildlife's conservation office at the DOE, said that “We must admit that if agricultural, industrial and other poisons were directly released into the water, other aquatic species, including fish, would also have been killed, while the large population of the deaths is related to shorebirds.

While Issa Kalantarai, head of DOE, believes that the lack of upstream water in Miankaleh wetland is the reason for the loss of birds.

Montazemi earlier told ISNA that large numbers of migratory birds were killed in shallow areas where oxygen was likely to be unavailable, so it could even be said that lack of water flow to the wetland could create anaerobic conditions and produce botulinum.

Investigation needs to be continued

According to ISNA, the DOE is reporting that bird deaths in Miankaleh have plummeted, and hopes that this will not happen again in the future, while there are still doubts and questions about the cause of deaths in the area.

Excessive hunting in migratory birds’ habitats in the country has made the Convention on Migratory Species to warn some countries about this issue, which has always been a global threat to biodiversity and has attracted international attention.

Now, along with illegal hunting, there are other environmental threats, including water pollution and wastewater flow, lack of provision of wetlands’ water right, etc. So, it is expected that the DOE carefully investigate and not allow that the migratory birds habitat management gets out of control more than ever.

FB/MG