Winter nests of the hedgehog (Erinaceus europaeus L.)

Summary An account is given of the winter nests of the hedgehog (Erinaceus europaeus L.), and their importance in the life of this species.Nests were constructed for protection during hibernation, in sites chosen for the degree of support gained from surrounding objects. They were usually made mainly of dry leaves, specially selected and carefully built into a robust weatherproof structure, by a method appropriate both to the hedgehog and the materials used. Construction of winter nests was closely correlated with environmental temperature.The life history of hibernacula is reviewed and it is shown that nests may persist for well over a year, though the leaves of which they are made normally decay completely in a much shorter time. Nests built in brambles, with plenty of support last longer than those in less preferred sites.The construction of winter nests was strictly seasonal, but their decay was gradual, with rapid deterioration at the end of the winter. About 30% of nests persisted till the following winter, though were not re-occupied.Over half of the nests built were occupied for one month or less, though some were in continuous use for up to six months. New nests were built even in midwinter, but the likelihood of their being occupied immediately was affected by the weather. Hedgehogs rarely shared a nest, though empty nests were sometimes taken over by small mammals or Hymenoptera.Most hedgehogs that died in their nests during winter were juveniles perhaps too inexperienced to construct an adequately protective nest.The importance of the nest in a hedgehog's life, particularly during hibernation may be a significant feature in determining both its distribution and its habitat choice.     

Further studies on the neurohypophysis of the hedgehog (Erinaceus europaeus)

Summary Further studies of the neurohypophysis of the hedgehog have confirmed the presence of two distinct types of neurosecretory fibre in the infundibular process. A third type of fibre, possibly containing catecholamines, is found in the upper infundibular stem.Lesions of the paraventricular nuclei result in vacuolation of type I nerve fibres, which contain crystal-like and aggregate bodies. Type II fibres, containing membranous inclusions, with or without osmiophilic material, apparently do not degenerate. The evidence suggests that type I fibres arise in both the paraventricular and supraoptic nuclei.Dedicated to Professor Berta Scharrer on the occasion of her 60th birthday.     

A study of home range and movements in the hedgehog (Erinaceus europaeus)

Radio-tagged hedgehogs were studied on an area of traditionally managed farmland to obtain information about distances travelled and range areas used per night in this habitat. Data from five animals were obtained on 62 hedgehog/nights. Twelve of the data sets were eliminated owing to their incompleteness; observations of three animals (totalling 45 hedgehog/nights of acceptable data) were critically examined to establish basic procedures for future comparative studies. The concept of 'home range' is discussed in relation to the duration of study periods.     

Circannual changes in blood coagulation factors and the effect of warfarin on the hedgehog Erinaceus europaeus

Levels of blood coagulation factors were measured monthly in hedgehogs kept at 20 degrees C under a natural-light schedule for 1 yr using prothrombin time and the P & P method. Hedgehogs display a circannual cycle of blood coagulation factors in the absence of temperature cues, with high levels corresponding to the active period and low levels corresponding to the hibernation period. Ten hedgehogs and ten guinea pigs were treated with clinical doses of warfarin and blood coagulation factors measured. Warfarin caused a similar decrease in vitamin K-dependent blood coagulation factors in both species.     

Genetic differentiation among local populations of the European hedgehog (Erinaceus europaeus) in mosaic habitats

Tissue samples from 160 European hedgehogs, Erinaceus europaeus , representing eight small populations from a highly fragmented landscape in Oxfordshire, UK, were screened for polymorphism at six microsatellite loci. Permutation analysis of allelic compositions revealed no evidence for linkage disequilibrium among loci. Genotype proportions within populations and at five loci did not differ from those expected at Hardy–Weinberg equilibrium. However, significant heterozygote deficit and amplification failure of several samples necessitated removal of one locus from the analysis. Mean observed heterozygosity was 0.70. Average Rho _ST was 0.079 and differed significantly from zero, suggesting restricted gene flow among local populations. Pairwise Nm values and geographical distance were not correlated, indicating that factors other than distance affected dispersal.     

Seasonal ultrastructural changes of the hypophyseal pars tuberalis in the hedgehog (Erinaceus europaeus L.)

The comparison of the hypophyseal pars tuberalis in active and in hibernating hedgehogs reveals different cytological characteristics in the specific secretory cells. In active animals, these cells show oval nuclei and the cytoplasm contains numerous secretory granules near or attached to the cell membrane, suggesting exocytotic release. In hibernating animals, the specific secretory cells are characterized by irregularly shaped and often invaginated nuclei. Clusters of secretory granules lying within the cytoplasm are often joined by lysosomes. These areas are observed to be encircled by cisterns of the endoplasmic reticulum. Degenerative processes in the structures sequestered in this way are interpreted as signs of crinophagy which has no equivalent in the cell types of the pars distalis.