Morris (1973) hedgehog winter nests

Title: Winter Nests of the Hedgehog (Erinaceus europaeus L.), Oecologia (Berl.) 11; 299-313. 1973

Authors: P. Morris

Country: UK

Background to study

An investigation into the ecological features of winter nests of the hedgehog and their importance in the life of this species and thus, their distribution and habitat choice.

Method

• Nest searches, conducted by two people, were carried out within two narrow strips of woodland with bramble and herb understorey, in Bushy Park London between 1963 and 1967.
• 185 individual nests were identified and monitoring at six-weekly intervals during the study period. 
• A description of the physical condition (inside and out) of each nest and whether it was occupied or vacant was recorded during each visit and from 1966 the entrance directions of each nests and nest temperature was additionally monitored.
• Average number of hedgehogs and nests present per month (including those not recorded but present during the proceeding and preceding survey sessions of the same year); average number of freshly built nests per month, nest structure, location and longevity and occupation of nests by hedgehogs were assessed to determine the ecological features of winter nests for hedgehogs. 
• Results were in concordance with nests reported elsewhere.

Key results

• Hedgehogs build nests throughout the winter (25% in November) and are stimulated to build new or repair existing nests using new materials during mild conditions, when aroused from hibernation.
• Arousal from unsheltered nests during winter may be stimulated by warmer daytime temperatures.
• 60% of nests were occupied for <2 months and of these half were never occupied.
• The number of nests exceeded the number occupied by hedgehogs suggesting spare nests are built.
• Nests are at ground level, measure 30-60cm diameter and consist of a chamber encased by <20cm of closely flat packed deciduous leaves (Sycamore and Turkey oak, least preferred) which form the walls.
• Nest degradation is accelerated following snow melt or wet weather and when built from grass.
• Average nest longevity was 6.4 months, can exceed 12 months but half lasted fewer than 5 months.
• Hedgehogs preferred nest sites located underneath bramble which survived on average more than 7 months, potentially due to the elastic pressure of brambles that allow for tighter compaction of leaves which reduce decomposition.
• Nest occupation was highest in nests of good condition and during periods of low temperatures.
• Nest sharing is uncommon but does occur.
• Ticks, the hedgehog flea (Archaeopsylla erinacei Bouché), mites (Acari) and the pathogenic dermatophyte Trichophyton erinacei can be present in hedghog nests.
• Hedgehog nests provide habitat for ground nesting bees, wood mice, short tailed voles and wasps.

Key messages to landowners and managers derived from these results

• Hedgehog nests can be identified by their size and structure and surveys should focus on areas underneath structural support such as bramble and log piles.
• Leaf litter is an important nesting resource for hedgehogs throughout the winter and should be either left or collected into piles near to potential hedgehog nesting sites, such as tree lines, copses or hedgerows.
• Sheltered areas with bramble should be established and/or maintained as these provide important hibernacular sites that have increased longevity and lower daytime temperatures which may reduce arousal and thus risk of mortality of hedgehogs overwinter.
• Management of scrub overwinter should be sensitive to hibernating hedgehogs.
• Unocuppied hedgehog nests, if encountered, should not be removed or disturbed.
• If handling hedgehog nests, preventative measures, such as wearing disposable gloves, should be taken to avoid transmission of ectoparasites, particularly “hedgehog ringworm” (Trichophyton erinacei Padhye).