Common shrew  (Sorex araneus)

Echolocation: Detecting objects by reflected sound. Used for orientation and detecting and locating prey by bats and cetacea (whales and dolphins).
Genus: A category used in taxonomy, which is below 'family' and above 'species'. A genus tends to contain species that have characteristics in common. The genus forms the first part of a 'binomial' Latin species name; the second part is the specific name.
Hibernate: A winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
Ultrasound: Sounds that are above the range of human hearing.

1. Animal Diversity Web (July, 2002)
   http://animaldiversity.ummz.umich.edu/accounts/sorex/s._araneus$narrative.html
   
2. The Mammal Society. Mammal Factsheets. (July, 2002)
   http://www.abdn.ac.uk/mammal/common_shrew.shtml
   
3. Churchfield, S. (1988) Shrews of the British Isles. Shire Natural History Series No 30. Shire Publications, Princes Risborough.
   
4. The Environment Agency. (1998) Species and Habitats Handbook. The Environment Agency, Bristol.
   
5. Macdonald, D.W. and Tattershall, F.T. (2001) Britain's mammals- the challenge for conservation. The Wildlife Conservation research unit, Oxford. Available at:
   www.wildcru.org
   
6. Burnie, D. (2001) Animal. Dorling-Kindersley, London.