At least 77 animals, birds and reptiles died in Mumbai’s Veermata Jijabai Bhosale Udyan – better known as Byculla zoo – in 2016-17, according to the Central Zoo Authority’s inventory report. Animal activists claimed lack of maintenance and the deplorable state that the zoo was kept in was responsible for these deaths, the Hindustan Times reported on Monday.

The number of animal deaths at the Mumbai zoo has been increasing steadily since 2011. In 2015-16, 70 animal died at the zoo, 72 in 2014-15, 40 in 2013-14, 39 in 2012-13 and 34 in 2011-12. The current population of animals, birds and reptiles at the establishment is 388, including 152 exotic species.

Zoo officials claimed that most of the deaths were because of old age and natural causes. Byculla zoo Director Dr Sanjay Tripathi told the Hindustan Times that proper medical treatment was provided and all cases were given “individual attention”.

However, Sunish Subramaniam Kunju, secretary of the Plants and Animals Welfare Society, said the pollution during the zoo’s renovation had led the animals to die. “The constant movement of trucks within the zoo premises led to both air and noise pollution,” he said. “Improper management of cages and insufficient treatment of water bodies has led to the deaths.”

The PAWS-Mumbai secretary said they will raise the matter with the Maharashtra Forest Department. Forest Minister Sudhir Mungantiwar told the Hindustan Times that the mortality rate at the zoo was worrisome, but its management was the Brihanmumbai Municipal Corporation’s responsibility.