The twisted mesh of the enclosure where thieves struck. (Aranya Sen)

Eight rare monkeys the size of large rats and worth around Rs 1 lakh each in the illicit wildlife market were stolen from Alipore zoo early on Sunday.

The theft was the first in the history of the 133-year-old zoo, though not the first attempt to steal a common marmoset (Callithrix jacchus). A lone thief was caught stealing a marmoset, a native of Brazil with grey heads and a pair of furry white ears, in March.

A team of 14 guards was on duty between 10pm on Saturday and 6am on Sunday but none of them knew about the theft until a zoo employee found eight marmosets missing from the enclosure around 8.30am.

Guard Ashok Patra, whose duty it was to keep watch on that enclosure, has been detained. “A probe has revealed that Ashok was asleep when he should have been guarding the enclosure. We are trying to find out whether he has any links with the thieves,” a police officer said.

S.K. Chowdhury, the director of Alipore Zoological Gardens, said four adults and as many sub-adults were stolen. “They weigh between 500 and 700gm and were donated to us by the Delhi-based Institute of Immunology in January 2001,” he told Metro.

The zoo has eight more marmosets in an enclosure at Balaram House, barely 400 feet from the shed that was raided.

A marmoset in the other enclosure

Sanjay Kumar Ram, 32, who would feed the stolen marmosets, was on his morning round when he saw the enclosure empty and immediately raised alarm.

A preliminary investigation revealed that three to five thieves, armed with wire-cutters, scaled a boundary wall to enter the campus between 1am and 3am. “After reaching the shed housing the eight stolen marmosets, a couple of the thieves scaled the nine-foot gate and cut the wire mesh. The small opening was enough to take out the tiny primates,” a zoo official said.

A city-based private agency — Bright Security Placement Services — has been guarding the zoo over the past four years. The agency deploys 20 personnel for the 9am-5pm shift and 14 for the 10pm-6am vigil. Two of the night guards are exclusively for the marmoset enclosures.

Police officers blamed the zoo authorities for the security lapse that allowed the thieves to enter and leave the zoo unnoticed.

The police have alerted all 48 police stations in the city about the theft. “We have also asked railway police to look out for the stolen animals at Sealdah and Howrah stations,” an officer of the detective department said.

Animals like marmosets are prized by collectors and illegal breeding centres.