Three proven methods of bait distribution were used in the REP:
- Hand broadcast - in the settlement area
- Locked bait stations - in the settlement area
- Aerial distribution - in the uninhabited mountains
Two applications of aerial baiting were distributed (14 to 21 days apart, depending on the weather). Most rodents were likely killed by bait from the first bait drop.
A second bait drop eliminated the likelihood of any gaps in the distribution of baits and ensured bait was available long enough for all individuals to receive a lethal dose.
Aerial baiting technique
The REP operation was primarily implemented over April - December 2019, as the availability of natural food for rodents is low during winter, rodent breeding is reduced, and rodent populations are at their seasonal lowest.
Winter is also a period when most non-target seabirds are absent from the LHI Group.
Bait drops were timed to avoid periods of predicted heavy rainfall, which could have prematurely dissolved the bait. Drops could not take place in high winds or in the presence of low clouds.
The initial bait drop commenced on Saturday June 8, 2019, in fine weather, and was finished on Monday 10 June 2019.
The second drop commenced on June 30, 2019, and was completed on Monday 8 July 2019.