Aspects of the ecology of ground-active spiders (Araneae) of the Karori Wildlife Sanctuary, Wellington

Abstract

Ground-active spiders were sampled using pitfall traps over a period of 11 months in three forest types in the Karori Wildlife Sanctuary, Wellington. A total of 605 adult spiders were caught, belonging to 44 species, all but one of which were indigenous to this country. Each species was assigned to a guild based on foraging behaviour. The ground-active spiders caught in the Karori Wildlife Sanctuary were found to be similar in family composition and to have approximately 50% of species in common with spiders caught in pitfall traps in the Orongorongo Valley, near Wellington. The abundance of adult spiders in the traps in this study was low in comparison to the numbers caught in pitfall trap studies performed in other countries. Habitat associations of the common spider species caught were analysed using classification trees and correlation coefficients. Many species were found to be associated with features of the litter environment. Some of the associations reinforced what is already known about certain species. Further research is required to determine the validity of the habitat associations presented in this study. An analysis of the seasonal variation in the activity of some of the spider species caught found that many were aseasonal. However, the male spiders of many of the larger species had a discrete period of activity, while the females occurred over a wider range of months. The majority of the species were caught in numbers too low for any comments to be made on their seasonality. A comparison of the ground-active spider fauna of native and exotic forest types found a greater diversity in the native forest, although abundance was high in the exotic pine forest. An important difference between the spiders of the two forest types was that small spiders of the web guild were dominant in numbers in the pine forest and larger spiders of the vagrant guild dominated in the native forests. These observations are characteristic of conifer and broad-leaf forest types in other countries.