Snacks in the city: the diet of hedgehogs in Auckland urban forest fragments

Urbanisation causes fragmentation of natural habitats, which results in loss of biodiversity, while promoting an environment that can facilitate invasive species. However, forest fragments are an important refuge for native species and therefore understanding and mitigating threats in fragments is critical. While the impacts of some mammalian pest species, such as rats (Rattus spp.), are relatively well-known in New Zealand, hedgehogs (Erinaceus europaeus) are relatively understudied invasive mammals, and their impacts in urban fragments are unknown. Hedgehogs are abundant and widespread in New Zealand, with a relatively broad diet that can include invertebrates, lizards and bird eggs. We examined the stomach contents of 44 hedgehogs collected from 10 forest fragments in urban Auckland, New Zealand. Hedgehogs were feeding predominantly on invertebrates (Coleoptera, found in 53% of stomachs; earthworms, 43%; slugs, 23%), but also weta (13%), giant centipedes (5%), birds (7%) and lizards (2%) at lower frequencies. Hedgehogs are likely to be affecting community composition primarily through predation of invertebrates, with unknown effects on their populations.