An exploratory investigation of glucocorticoids, personality and survival rates in wild and rehabilitated hedgehogs (Erinaceus europaeus) in Denmark

Background: The European population of hedgehogs (Erinaceus europaeus) is declining. It is therefore essential to optimise
conservation initiatives such as the rehabilitation of sick, injured and orphaned hedgehogs. Wild animals placed in captivity
may be prone to chronic stress, potentially causing negative health effects. Therefore, the effects of these rehabilitation
efforts should consequently be evaluated. Furthermore, hand-raising orphaned hedgehogs is a laborious and costly
task, and it is therefore relevant to document whether they have equal post release survival rates compared to their wild
conspecifics.
The objectives of this research were therefore to conduct an exploratory study of glucocorticoid levels in hedgehogs from
different backgrounds and compare the post release survival of translocated, rehabilitated and wild, juvenile hedgehogs as
well as the possible effect on survival of differences in shy or bold behaviour (personality) exhibited by individuals.
Results: We measured glucocorticoid levels in 43 wild-caught (n = 18) and rehabilitated (n = 25) hedgehogs and compared
the post release survival and spatial behaviour of 18 translocated juvenile hedgehogs (eight hand-raised and ten wild)
until hibernation. The possible effect on survival of differences in shy or bold behaviour (personality) exhibited by 17 juvenile
individuals (seven hand-raised and ten wild) was also examined.
Rehabilitated individuals and females had higher levels of faecal corticosterone metabolites compared to wild individuals
and males, respectively. Rehabilitated individuals showed higher levels of saliva corticosterone than wild. The personality
tests labelled 13 individuals as shy and 11 as bold. Post release survival was 57% for rehabilitated and 50% for wild individuals.
Neither background nor personality affected post release survival. Home range measures were 3.54 and 4.85 ha. Mean
dispersal length from the release sites was 217 ± 100 m.
Conclusion: The higher levels of corticosterone observed in rehabilitated compared to wild hedgehogs calls for consideration
of the duration of admission to wildlife rehabilitation centres to reduce stress levels in the patients.
Hand-raised juveniles appear to have the same prospects as wild, and personality does not seem to affect post release survival
in hedgehogs, indicating that hand-raising of orphaned juvenile hedgehogs is a relevant contribution to the conservation
of this species.