Social aggregation behaviour in the North African amphisbaenian Trogonophis wiegmanni

Abstract

The ecology and behaviour of Amphisbaenians is poorly known due to their fossorial habits. However, amphisbaenians are often found under rocks where they thermoregulate, and probably engage in social interactions. We describe aggregations under rocks in a North African population of the little studied amphisbaenian Trogonophis wiegmanni. These observations could be used to make initial inferences about the social behaviour of this amphisbaenian. Results showed that amphisbaenians were sometimes found in pairs under the same rock. However, these aggregations were not random. Adult males were only found together with adult females, but we did not find pairs of adult males or adult females. This might suggest that there is intra-sexual intolerance, and that adult individuals of the same sex do not occupy the same rock space. Pairs of adults were more frequently found in spring than in autumn, coinciding with the mating season. Also, juvenile individuals were often found together with an adult, but juveniles tended to be more often with an adult female than with an adult male. This might indicate that juveniles are allowed to remain with their parents until they are older, which might enhance offspring fitness by providing access to high-quality habitats.

Keywords:

• Social behaviour
• rock use
• Chafarinas Islands
• Amphisbaenia
• Trogonophidae

ACKNOWLEDGEMENTS

We thank three anonymous reviewers for helpful comments. The personal and facilities of the field station of the ‘Refugio Nacional de Caza de las Islas Chafarinas’ provided logistical support. We thank Rosa Arribas, Javier Díaz and Gonzalo Martínez for friendship and help in the Islands. Financial support was provided by a contract from the Organismo Autónomo de Parques Nacionales (Spain), and by a Ministerio de Ciencia e Innovación project (MCI-CGL2008-02119/BOS).