Intra- and interspecific antagonistic behaviour in two sympatric species of water shrews:Neomys fodiens and N. anomalus

Authors:

• Natalia L. Krushinska,
• Leszek Stanisław Rychlik

Abstract

Ethological mechanisms which diminish the aggression and competition among sympatric Neomys fodiens (Pennant, 1771) [FF] and N. anomalus Cabrera, 1907 [AA] were studied in enclosure conditions. The animals were kept and subsequently tested (11 FF and 10 AA) in 1- or 2-species groups, in enclosures measuring 275×135 cm or 135×135 cm. During 240 h of direct observation, social behaviours and patterns of hiding-place usage by water shrews were recorded. Mutual avoidance (individual occupation of the nest boxes, territoriality, and spatial dispersion in the enclosure), active antagonism (threats, combats, chases) and absence of typical social hierarchy were the most characteristic intraspecific relations of FF. A high level of tolerance and group-occupation of the nest boxes were the most characteristic intraspecific relations of AA in socially stabilized communities. It seems that a group model of life without hierarchic relations is appropriate for this species. In mixed groups, FF dominated over AA. Over the course of time, the stabilization of interspecific relations and decrease of interspecific conflicts were observed. This may be the result of the habituation of one species to the presence of another, and of active avoidance of predominant species by submissive species (assemblage in 1 nest box, maintenance of distance), in which the same, or very similar, communication systems could be involved. © 1993 Japan Ethological Society.