How Many Kiwis Does it Take to Screw With a Bulbul?

According to this story from stuff NZ, Biosecurity New Zealand has alerted residents of Auckland to be on the lookout for a pair of red-vented bulbuls (Pycnonotus cafer) that were seen in the area. BNZ is concerned that a viable population of the birds would cause damage to agricultural crops and to the natural environment as well. Red-vented bulbuls were previously introduced to New Zealand back back in the 1950s but were eradicated - their importation was later banned. Sources differ regarding whether the species has already reestablished in that country.