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The postnatal growth period is of central interest for an understanding of the life histories of altricial mammals . Among the soricine shrews (Soricidae, Insectivora), however, there is only limited information available concerning the postnatal development of a few species (Crowcroft 1957;Harper 1977;Churchfield 1990;Innes 1994). In the long-clawed shrew Sorex unguiculatus Dobson, for example, there have been no reports of direct observations of postnatal growth and development although Okhotina (1984), Inoue (1990), and Nesterenko (1999) estimated the length of the postnatal period of this species, inferring from indirect observations. In the present paper, we describe our direct observations of the growth and development throughout the postnatal growth period of captive S. unguiculatus. Materials and methods A pregnant S. unguiculatus that had over-wintered was captured in the Experimental Forest of Forestry and Forest Products Research Institute in Sapporo on 31 August 2000.Immediately after capture, she was moved to a laboratory at the Institute of Low Temperature Science, Hokkaido University, Sapporo , where she gave birth to six neonates in the early morning of I September 2000.The family of shrews was kept in a semi-open house under natural conditions of temperature and daylight. A mixed paste diet (Ohdachi 1994) and water were supplied ad libitum. In addition the artificial diet was supplemented with living earthworms (Lumbricidae) or frozen silkworm (Bambyx man) pupae every day. At first, the mother and neonates were kept together in a plastic cage (35 em L x 20 em W x 25 em H), containing a wooden nest box, an exercise wheel, and sawdust on the floor (see Ohdachi 1994). They were moved, when the young became 23 days old, into a larger cage (65 em L x 35 cm W x 35 em H), containing four nest boxes with IO-cm deep soil covered with sawdust. Food and water trays were placed near each nest box. The young were separated from their mother and kept individually once they were 29 days old.Once neonates reached three days old they were weighed to the nearest 0.1 g using a portable electronic balance every second day. Body length was measured every third day by placing a neonate on a sheet of graph paper (I mm x I mm square). As individual siblings were not marked, individual growth could not be followed, except for those individuals iden tifiable by particular physical features. In this report, the sex of the newborn shrews was not determined .

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