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by Marina KOLOTOVA, laboratory assistant, Oka Biospheric State Preserve
These nice inhabitants of forests, steppes and deserts - hedgehogs - belong to one of the most ancient species of placenta insectivorous mammals and as such are of great interest to science. It is probable that in the near future they will become indicators of the general state of the biosystem. There exist seven hedgehog species on the terrirory of the former Soviet Union: common, southern, Caucasian, Amur, Dauri, big-eared and bald (or dark-quilled) ones. Unfortunately, some of them are on the verge of extinction: the first of them has been registered in the Red Data Book of ICNP and the Dauri one in the Red Data Book of the USSR.
The orginary hedgehog can be found all over the territory of Europe. In the Alps hedgehogs have been encountered at altitudes of some 2,000 m and in the Caucasus of up to 3,000 m.
Hedgehogs' favourite habitats are fields, groves, gardens, thickets of bushes and weeds. As a rule they dwell in solitude, but join in pairs during the mating periods. They are usually active at night and during the day they stay in holes or thickets of bushes. Sometimes these animals dig holes for themselves. Female hedgehogs usually dwell with the male, but sometimes they provide for themselves a separate and rather specious nest, covered with leaves, hay and moss. In such dwellings hedgehogs hibernate from the onset of the cold season till spring.
The mating period begins in late March. Seven weeks after mating the female gives birth to up to eight cubs-blind, completely naked and white in color. They reach pubescence only at the end of the first year of life and their life span is from 8 to 10 years. Hedgehogs have no problems accomodating themselves to captivity.
Apart from insects and worms, the diet of the common hedgehog also includes snails, mice, snakes and small birds and their eggs and some fruits. By destroying the larvae of May bugs and other harmful insects and also mice and poisonous snakes, hedgehogs do much good to man. On the other hand they can be the "intermediate" carriers of ticks which spread piroplasmosis* of domestic animals. And hedgehogs possess unique immunity to potassium cyanide and adder venom, a unique feature which holds out a promise of some important medical discoveres.
Unfortunately, the common hedgehog as a species has not been studied well enough and we in our preserve have no statistics on its population, sex and age composition, morphometry, biology, ecology, and movements. The most comprehensive studies on that score were conducted back in 1924 by Dr. Sergei Turov in the Ryazan region and neighbouring areas. He investigated the natural habitat and propagation of two local sub-species: the European and the Southern ones. In some areas of the region, the scientist noted, he encountered the latter species only, and he gathered data on its biology and body shape and size.
1996 saw the beginning of systematic studies on the territory of the Lakashinsky forest area of the Oka biospheric preserve. And the scientists registered a sharp drop in the hedgehog populations: a total of 8 in 1996, 4 in 1997 and only 2 in 1998. Among the causes were the drought of 1995-1998 which left the animals without the sources of food so that they either perished or had to migrate to other places. The second reason was what was called the sanitary thinning of the local forests in the summer of 1997-1998.
Detailed studies of the common European hedgehog were started in 1999, with emphasis on forest areas 49 and 50 where most hedgehogs dwelled in the previous years. But only 6 were found there this time and
* Piroplasmosis - tick fever caused by infection with pathogenic protozoa.- Ed.
one more in the eastern section of Quarter 26.
The search for hedgehogs was conducted with the help of a specially trained dog along stretches of some 200 meters wide. The scientists recorded the time of the beginning and the end of their investigations and marked on the map the places were the animals were found. The caught hedgehogs were brought back to the lab where they were marked, measured and their age, sex and colour were recorded. Researchers registered the physiological conditions, such as weight and health of the male and female, reproductive organs and nipples. The labelling was done in the commonly accepted way (amputation of toes) with some modifications in view of the scarcity of the species.
On the following day researchers checked on the healing after the amputation, weighed the animals and released them exactly on the spots where they had been caught. During the following period the animals remained under visual observation, their routes were observed and measured. Simultaneous phonological* observations were conducted along the routes and experimental lots.
The first of these hedgehogs was traced in Quarter 49 on April 8. On April 17 the tracker dog discoverd a male, registered under Number 2, and the first female, (Number 3), which was pregnant, was found on June 12 in Quarter 26. One month later the dog found in the Brykin Bor village a female with a cub, and on July 23 and 26 (in Quarters 49 and 50) - two independent cubs. They were very exhausted and could hardly move. One of them was saved, but the other perished. Among the discovered animals males prevailed in proportion of 6:2. In 1999 the last hedgehog was spotted in the Brykin Bor forest on October 5.
All of the labelled animals belong by their appearance to the Southern species of the common European hedgehog-something that bears out the results obtained by Dr. Turov. Scientists conducting these studies found out that the best time for tracing these animals is from 7 p.m. until darkness. As for the territorial distribution of the labelled animals, three were traced in Quarter 49, two in Quarter 50 and one in Quarter 26. All of these areas are covered with forests of the same basic type, have elevated relief and weakly or medium podzolic sandy soil and ground water at the depth of more than 2 to 3 meters. The main tree species are pines of about 100 years of age and 26 meters high, and there are pines which are 25 years of age and 5 meters high. The under-brush of medium thickness consists of mountain ash and juniper and the ground is covered with green moss, lily of the valley, fern and heather-a combination which seems to meet best the requirements of the animals under investigation. And although this kind of environment also exists in other areas covered by the investigations, no hedgehogs were found there during the same time of the year and in the same hours. That means that there must have been other factors involved which, however, escaped our attention.
* Phenology - branch of science dealing with the relations between climate and periodic biological phenomena (as bird migration and plant flowering). - Ed .
The statistical number of animals is calculated for 10 hectares of land. For our studies in July 1999 it amounted to 0.82, but taking into account the time spent on the assessments, the final results are even more discouraging - only 0.0126 hedgehogs per 10 hectares per hour of studies.
Interviews with Brykin Bor residents revealed that over the past few years hedgehogs were encountered more often than before within the confines of the village. So far we can not tell whether this has been the result of the droughts affecting the local forests or there exist side by side two very different hedgehog populations (one adopted to human environment and the other to life in the forests). And there is no denying the deplorable fact that to this day there are more questions than answers concerning the present and the future of the hedgehog here.
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