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

Abstract

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.

Detecting small and cryptic animals by combining thermography and a wildlife detection dog

“…This may include research on many endangered farmland species such as Eurasian skylarks (Alauda arvensis), grey partridges (Perdix perdix), Northern lapwings (Vanellus vanellus) or European hamsters (Cricetus cricetus), but also, on species outside the farmland context such as for example sand cats (Felis margarita) in the desert, bird nests on cliffs, or hedgehogs (Erinaceus roumanicus) in the park. Another field of application is the detection and elimination of invasive species 17,3738 . thermal imaging: general.…”

“…Thermal imaging techniques to study wildlife were first tested in the late 1960's on white-tailed deer, Odocoileus virginianus 13 , and have afterwards been used to detect, survey or observe a range of different mammals, birds and invertebrates 12 . To date, the smallest mammals that have been systematically studied using thermal imaging are ungulate fawns, adult hares (Lepus europaeus), adult rabbits (Oryctolagus cuniculus) and hedgehogs (Erinaceus europaeus) [14][15][16][17] . However, some studies have reported a rather low detection rate, stressing the fact that alternative approaches are needed 15,18 .…”

Comparing non-invasive surveying techniques for elusive, nocturnal mammals: a case study of the West European hedgehog (Erinaceus europaeus)

“…Finally, Morris (1988) also mentions success in finding hedgehogs with a dog although this is not described in detail. IRT cameras have been used successfully in Regent's Park, London, UK (Bowen et al 2019) and forest fragments in Auckland, New Zealand (Nottingham et al 2019). Conversely, Haigh et al (2012) concluded that the IRT camera that they used was ineffective.…”

The impact of mammalian insectivores Rattus rattus (Rat), Mus musculus (Mouse) & Erinaceus europeus (Hedgehog) on the size and abundance of mainland Coleoptera and Orthoptera

“…Hedgehog behaviour and dietary preferences would suggest that increases in beetle could be a significant driver of increased hedgehog tracking. Unlike rats and mice which are generalist omnivores, hedgehogs are primarily insectivorous with invertebrates making up the bulk of hedgehog diets (Hendra, 1999;Nottingham et al, 2019). Beetles in particular have been found…”

“…Unlike other introduced mammals which show greater omnivory and rely more heavily on fruits and vegetation for food, hedgehogs primarily feed on invertebrates which can account for around half of the relative volume of hedgehog stomach contents (Nottingham et al, 2019).…”