Interspecific social relationships in three murid species of Central Argentina, after fasting and unlimited food

CUETO G.R; BILENCA, D.N; KRAVETZ F.O.

BEHAVIOUR

E. J. Brill

Lugar: Leiden, The Netherlands; Año: 1995 vol. 132 p. 811 - 820

0005-7959

We studied the social interactions between Akodon azarae and Calomys laucha, and between A. azarae and Oligoryzomys flavescens, by means of experimental confrontations under laboratory conditions. Trials were carried out after two treatments : in the first one (´food´ treatment), the animals were offered food ad libitum permanently, whereas in the other (´fast´ treatment), the animals were previously submitted to fasting for 30 hours. The largest species-A. azarae - dominated the other two species, being dominant in 69.6% of the aggressive interactions in which a clear dominant/subordinate relationship was detected (N = 79). During the ´fast´ treatment, A. azarae fed longer than C. laucha and O. flavescens, and it was the only species which significantly increased its feeding time with respect to ´food´ treatment. There were higher frequencies of aggressive interactions in A. azarae - C. laucha trials than in A. azarae - O. flavescens trials. Comparisons of the behavioural variables between C. laucha and O. flavescens during their respective confrontations with A. azarae showed that C. laucha had significantly higher median values of freezing and walking behaviours, whereas O. flavescens showed a higher frequency of alertness. Species differences found in the laboratory support the interpretation that A. azarae is usually dominant over C. laucha and O. flavescens, and that A. azarae has the priority of access to food sources in situations of food shortage (winter) by means of its social dominance over the other two species. We suggest that the differences in the behavioural reactions of the subordinate species when meeting the dominant one may help to explain the different scales of spatial segregation that C. laucha and O. flavescens maintain with A. azarae in the field. IF 06 1.165; 2do tercio Zoology