Abstract:
Little Barrier Island or Hauturu, is one of a New Zealand’s few offshore islands outside swimming distance of mammalian predators, and as a result is a key refuge for a range of threatened species. The island consists of a range of northern New Zealand habitat types which have had little phenological research in the past. This thesis addresses the temporal and spatial variation in plant phenology on Hauturu, and how this influences both past and future kakapo (Strigops habroptilus) reproductive success. From July 1991 to December 1995 historical phenological data of over 80 plant species were collected by Ron Moorhouse et al. This thesis consists of the analysis of these data, in relation to the breeding patterns and habitat selection of kakapo that were present during this time. Present-day phenological data were also collected from November 2011 until April 2012, to compare phenological patterns and assess the future reproductive capability of newly reintroduced kakapo. During the 1991-1995 dataset there was significant inter-annual variation in plant phenological amplitude, with a peak in plant productivity in 1993 and lower overall amplitude in 1994 and 1995. While 1995 had a lower overall amplitude, with fewer species fruiting, these species still produced abundant fruit crops, indicating a ‘mast’ seeding year. This indicates that both general flowering and ‘masting’ phenological patterns play an important role on Hauturu. During their initial occupation of the island, female kakapo, particularly breeding females, showed a significant preference for kauri-dominated forest. Kakapo attempted breeding in two of the five years in which phenological data were collected, 1993 and 1995. Plants that produced an abundant fruit crop during these years included kauri (Agathis australis), a suspected kakapo breeding trigger. There has been an increase in overall phenological amplitude on Hauturu between the 1991-1995 and the 2011-2012 sampling periods, which may be related to either climatic changes or changes in predation pressures due to the eradication of kiore (Rattus exulans) and subsequent pollinator abundances. The ability of kakapo to maintain a breeding population on Hauturu may therefore have increased, although future phenological observations will need to be collected to monitor future breeding activity in relation to phenological patterns.
