Dickman (1988) Hedgehog age-related dietary changes
Title: Age-related dietary change in the European hedgehog, Erinaceus europaeus, Journal of Zoology, London 215; 1-14, 1988
Authors: C. R. Dickman
Background to study
An investigation into the dietary differences between different age classes of hedgehogs occupying rural and suburban habitats in England.
- 109 hedgehog carcasses were obtained from suburban and rural habitats, preserved in ethanol and their stomach and small and large intestine contents examined.
- Each individual was aged (annual age classes 1 – 7 yrs) by assessing the degree of ossification of epiphyseal cartilage in the forefeet and by counting age rings in sections of the periosteal bone of the jaw.
- Food material was assigned to 1 of 19 categories of prey type and 9 categories of prey mass and minimum numbers were scored for most types of prey.
- The mass of prey items was estimated for ingested fragments by comparison with whole specimens.
- Niche breadths were calculated using Levin’s index (1968) which accounts for the number of items ingested to those available and when 1.0 indicates all food types are used in equal proportions.
- Niche overlaps were calculated using Pianka’s symmetrical index (1974) which accounts for the proportion of type or size of food items ingested by different age classes and when 0 indicates that there is no overlap in food types eaten by two comparative age classes.
- Dietary differences between rural and suburban hedgehogs were observed with suburban hedgehogs having a higher relative abundance of fruit, isopods and tipulid larvae in their diets and with rural hedgehogs having a higher relative abundance of lepidopteran larvae.
- Prey weighing 0.05 – 0.49 g were taken most frequently by all individuals and the size of prey taken was positively correlated to age class.
- Young animals take similar numbers of prey items to older animals but take them from the entire prey spectrum, whilst older animals specialise in a narrow range of prey types.
- Hedgehogs attain their maximum body size at 2-3 years suggesting that dietary changes reflect improvements in foraging efficiencies with age and not body mass.
- Niche partitioning amongst age classes are likely to have evolved due to intraspecific competition and weak interspecific competition allowing hedgehogs to exploit a wide range of prey items.
Key messages to landowners and managers derived from these results
- Management actions that increase the diversity of invertebrate species are recommended to allow for niche partitioning amongst different age classes of hedgehogs and include but are not limited to:
- Environmental Stewardship Schemes that include buffer strips, establishing and managing hedgerows, organic farming and beetle banks.
- Improving connectivity between semi-natural habitat, particularly within urban areas where prey diversity may decline due to isolation.