Haigh et al (2012) hedgehog nesting behaviour bodymass Ireland

Title: Nesting behaviour and seasonal body mass changes in a rural Irish population of Western hedgehog (Erinaceus europaeus), Acta Theriologica, 2012

Authors: A. Haigh, R.M. O’Riordan & F. Butler

Country: Ireland

Background to study

An investigation into the nesting and hibernation behaviour and seasonal body mass changes of hedgehogs occupying rural farmland habitat in Ireland and how this varies with other studies in the UK and Europe.

Method

• Between 2008 and 2009, hedgehogs were captured during spotlight surveys, marked and monitored by radio-tracking within a 97 ha rural farmland site consisting of 23% arable, 64% pasture, 7% residential and small areas of scrub, marsh and wood.
• Captured individuals were weighed weekly (during summer), their sex determined and were classified as juveniles (<600 g, hind-foot =<3.6 cm and growing spines) or adults. Each individual was marked using heat shrink plastic tubes and by inserting a passive integrated transponder (PIT) into the upper hind leg.
• Eight hedgehogs were fitted with a tip light and their location was recorded every 10 minutes for consecutive nights between June and September 2008.
• Eight hedgehogs captured after September 2008 were fitted with a radio transmitter and were tracked before entering hibernation for 160 h over 33 nights and once entered into hibernacula, their location was checked at weekly intervals.
• The location of day nests and hibernacula was recorded.

Key results

• Day time nesting behaviour
  • 53% and 30% of 117 day nests identified were located in pasture and arable land respectively.
  • Hedgehogs returned to day nests in arable land significant more often than those located in pasture.
  • The majority of day nests were located within thick bramble along hedgerows.
  • Hedgehogs utilised up to 11 day nests between which they rotated on average 2.27 times and 1.34 times for females and males respectively and use of nests by different individuals was observed.
  • Females returned to the same nest on average 5.2 times which was significantly more often than males (3.8 times) and philopatry to nest sites rather than choosing the nearest was observed.
• Hibernacula nesting behaviour
  • 35% and 29% of 17 hibernacula identified were located in arable hedgerows and in scrub respectively. Only 6 of hibernacula were located in pasture hedgerows.
  • Four of six hedgehogs monitored, moved up to four times during hibernation between <3 hibernaculum and remained for significantly longer periods in hibernacula that was occupied during mid winter than early and late winter nests.
  • The mean length of hibernation recorded was 148.9 nights (October/November to March/April).
• Seasonal patterns in body mass
  • During summer adult males were significantly heavier (1026 – 1192 g) than females (878 – 1116 g) with the minimum body mass of females and males being observed in August and July respectively and a likely result of the reduction of pregnant females and courtship behaviour in males.
  • Both sexes were significantly heavier in the period approaching hibernation than in the other periods.
  • Juveniles showed a mean body mass increase of 7.78 g per day and doubled their body mass from first capture to hibernation (maximum weight attained = 1024 g).
  • During hibernation females lost significantly more body mass (15-38%) than males (3-6%).
  • A juvenile with a pre-hibernation body mass of 475 g survived hibernation.
  • Movement during hibernation increased the proportion of body mass lost.

Key messages to landowners and managers derived from these results

• Maintaining and re-establishing well connected hedgerows with bramble understorey and good ground cover within arable habitat is recommended to enhance the suitability of fields for hedgehogs both during summer foraging and winter hibernation.
• Unoccupied hedgehog day nests or hibernacula should not be disturbed.