August 30, 2016 10:57 AM EDT

Officers in New Zealand are investigating reports that 500 cows worth at least half a million dollars have been stolen from a Canterbury farm.

Locals said they’d never before heard of cattle rustling on such a massive scale, the Associated Press reports.

Willy Leferink, a friend of the farmer involved, said each milking cow was worth about 1,500 New Zealand dollars ($1,090) and weighed more than half a ton. He said the cows could have been taken from the herd of 1,300 near the town of Ashburton anytime between early July, when they were last counted, and late August.

He said the cows weren’t being milked because it was winter, but the farmer did notice they weren’t chewing through as much feed as normal.

“It’s unlikely the theft of hundreds of animals could be completed at once, and is more likely that multiple thefts could be carried out over a period of time,” Senior Sgt. Scott Banfield said in a statement.

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Write to Kate Samuelson at kate.samuelson@time.com.

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