Abstract:
Early European settlers introduced the European hedgehog (Erinaceus europaeus) into New Zealand in the late 1800s, which eventually became established nationwide. This is of concern for conservation programs, as they are known to compete with native species for food, carry human and stock infections, and are potentially a significant threat to native invertebrates and ground-nesting birds. A number of threatened ground-nesting native bird species nest in coastal sand dune areas within the greater Auckland region. This project encompassed a broad study of hedgehog ecology in coastal sand dunes to gather new information on hedgehogs in that habitat. Four coastal dune study sites in the Auckland region were selected: Tawharanui, Whatipu, Mangawhai and Papakanui Spit. Hedgehog home ranges and habitat use in dunes were studied using individual marking and radio-tracking. Mean home ranges of males were 16.7 ha and females 6.7 ha. Hedgehog home ranges were found to span up to 1.5 km, including to the shoreline, and some at Tawharanui overlapped shorebird nesting territories. Population density estimates of hedgehogs in dunes ranged from 0.17-0.97/ha. To determine available prey species, ground invertebrates present in each study area were surveyed using pitfall traps over two summers from August 2001 to July 2003. From this a reference collection of dune invertebrates was created. Hedgehog diet from these sites was investigated to identify their prey in this habitat. Large invertebrates such as scarab beetles, cockroaches, introduced gastropods and Lepidoptera larvae were the dominant prey items of hedgehogs. Evidence of predation on native skinks was also observed. Larger threatened invertebrates, native herpetofauna and shorebird nests were identified as potentially at risk of hedgehog predation, although vertebrate content was not seen to be a major part of hedgehog diet. Control measures are recommended where hedgehogs are present in association with threatened and protected native species.
