The Delhi zoo recorded 125 animal deaths in 2020-21, the lowest in the last three years, officials said here.
The zoo reopened to the public on Thursday after remaining shut for more than a year due to the coronavirus pandemic and bird flu.
Zoo Director Ramesh Pandey said the mortality rate for the last financial year ending Wednesday "hovered around 10 per cent", which is the lowest since 2017-18.
There are around 1,160 animals in the zoo at present. The final inventory report will be ready by mid-April, he told PTI.
The number of animal deaths in the financial year 2020-21 is "significantly less than last year" and it can be attributed to better monitoring and consistent efforts of the staff, Pandey said.
"The quarterly data is almost identical and there are no fluctuations, which indicates that no 'adverse event' took place," he said.
Pandey said the number of deaths could have been less had there been no case of bird flu.
The first case of bird flu was reported from the zoo on January 15, when a sample from a brown fish owl that was found dead in its enclosure tested positive.
Seven more samples from the zoo premises also tested positive over the next few weeks.
The zoo lost two tigress, a tiger and two cubs in the last one year.
It, however, added one Bengal tigress to the family in November last year and plans to bring in three more tigers from Chennai and Nagpur for breeding purposes.
According to official data, 172 animals died in the zoo in 2019-20 and the mortality rate was more than 17 per cent.
In 2018-19, the facility lost 188 animals and the mortality rate stood at around 15 per cent.
According to Pandey, 1,645 people visited the zoo on Thursday.
"We did not expect more than a hundred people (due to the pandemic), but the response has been excellent," he said.
Visitors reported minor hiccups in making online payments for tickets on the first day.
The visitors are required to buy ticket online on the zoo's website or at the entry gates using the QR codes.