Dowding et al (2010) hedgehog nocturnal ranging behaviour

Title: Nocturnal ranging behaviour of urban hedgehogs Erinaceus europaeus, in relation to risk and reward, Animal Behaviour 80; 13-21. 2010

Authors: C. V. Dowding, S. Harris, S. Poulton & P. J. Baker

Country: UK

Background to study

A study investigating the movement patterns of hedgehogs to determine how badgers, traffic and human activity and weather influence ranging behaviour and how hedgehogs have adapted their patterns of movement to living in urban environments.

Method

• 38 adult hedgehogs (19 males and 19 females) were located using spotlight surveys, radio tagged and tracked continuously between 2100 to 0300 hrs for 1-5 nights between May and September 2004 and 2005 in a 1.5 km² urban area of Bristol that consisted of residential, greenspace, allotments and cemetery.
• Fixes were obtained from 50 m or less, every 5 minutes and the location of individuals was allocated to a 25 x 25 m grid cell which was classified by habitat type, including back and front gardens of semi detached/terraced and detached houses, roads and road verges and other habitat.
• Minimum distance travelled between fixes, the % of fixes where animal was active, the area ranged (minimum convex polygon), the nightly range (area covered/night) and total range (pooled fixes) were recorded for each individual.
• Habitat preferences were measured by comparing habitat composition of pooled ranges with the habitat composition across the study site and preferential utilisation of habitat was measured by comparing % active fixes in each habitat with the availability of each habitat within each pooled range.
• The effects of weather and time of night on hedgehog movement acrivity was anslysed per half night.
• Road crossing occurrences were compared seasonally, between sexes, by time of night and avoidance of roads was measured by comparing number of actual road crossing by simulated random movement.

Key results

• Hedgehogs actively favoured the back gardens of semi-detached and terraced houses and females, not males, avoided the back gardens of detached houses which are associated with increased badger activity.
• Minimum distance travelled between fixes and nightly range area was higher for males (means = 861 m and 2.87 ha) than females (means = 514 m and 0.77 ha) and male, not female, activity declined during the course of the year.
• The activity of both sexes decreased with increasing body mass, significantly increased after midnight and increased with temperature which was more pronounced in females and for both sexes after midnight.
• Roads and road verges were actively avoided by both males and female hedgehogs but males were significantly more likely to cross roads than females, road-crossing tendency increased with increasing temperature and the frequency of road crossings by either sex did not differ significantly from that expected from random movement.
• Hedgehogs ranged significantly more widely/further in 2004 than 2005 whereas patterns in activity showed the opposite trend.

Key messages to landowners and managers derived from these results

• Hedgehog surveys should be carried out after midnight, during warmer weather and during breeding season (early summer) when hedgehogs are most active.
• Increasing accessibility of small residential back gardens should be encouraged to provide favourable foraging conditions for hedgehogs where risk of badger predation is reduced.
• Road crossings by hedgehogs form part of their nightly foraging activity, particularly during breeding when ranging is extended, thus research into road crossing structures that facilitate movement is recommended.  
• Inter-annual surveys are recommended for ecological studies as significant differences in ranging occur between years and a likely result of different environmental conditions.