Bait preferences in rabbits (Oryctolagus cuniculus) and non-target species in rabbit-prone areas of New Zealand’s South Island : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science at Lincoln University

Abstract

Rabbits (Oryctolagus cuniculus) are an introduced pest species that plagues New Zealand’s dryland and semi-arid environments. They are particularly abundant in areas of the South Island, including the Mackenzie Basin and Central Otago region. The current best practice for rabbit control is aerial distribution of carrot and cereal baits laced with pindone or 1080. Carrot tends to be the most preferred bait type; however, it poses issues in terms of its quick deterioration in field settings, as well as being costly and time-consuming to produce. With pest control in New Zealand focusing on eliminating predator-free species, there are large gaps in knowledge surrounding the development of more effective rabbit control tools, as well as the monitoring of non-target species present in rabbit settings. I conducted bait palatability trials, testing several novel and current baits to determine preferences in both rabbits and non-target species. An initial trial was run at Mt. Grand Station (Lake Hawea) in August 2023, testing four different bait types (fresh carrot, carrot jam, carrot oil mayonnaise (mayo) and RS5 non-toxic cereal pellets). Bait types were rotated through covered and uncovered bait stations. A further trial was run at Lilybank Station (Lake Tekapo) in October 2023, testing four bait types (fresh carrot, carrot jam, and two new cereal pellets A & B (formulated by Kiwicare), without using the covered bait stations. Interactions with all bait types were low. The bait types most interacted with by rabbits were fresh carrot and carrot jam. Visits were much more abundant than interactions. Rabbits visited carrot the most at Mt. Grand and cereal pellets B at Lilybank. Despite little consumption of bait types, they were still successful at luring individual rabbits to a site. Many non-target species were present in these rabbit environments. At Mt. Grand, blackbirds were the species that had the most interactions overall, mostly with carrot jam. At Lilybank, possums were the non-target that showed the most interactions, with the preferred bait type also being carrot jam. There was some neophobia toward covered bait stations, with visits at Mt. Grand decreasing as time went on, and interaction levels staying consistently low until the bait was placed outside the covered bait stations. At Lilybank (where covered bait stations were not used), there was a small increase in both visits and interactions over time. Activity data suggested that rabbits are most active around the sunset period and during the night. Further testing of novel bait without covered bait stations is required to better understand bait preferences without the effects of neophobia. The results produced by this study suggest that carrot jam or a bait type with high carrot content, should be successful at initiating pest rabbit interactions. However, further development and refinement is required to mitigate the risk associated with non-target species.