Scientists have been left baffled after a colony of native birds went missing

The Department of Conservation relocated 30 shore plovers from captive breeding facilities to Mana Island in February.

But the birds didn't settle down... they flew back to the mainland and all but three are presumed dead.

DOC's Troy Makkan says they aren't one hundred per cent sure why.

He says there may have been one strong bird that took off and the other followed - but they're also considering avian predation.