To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2007.04.014 Byline: Iva Dostalkova, Marek A pinka Abstract: Animals living in pairs often benefit from making behavioural switches synchronously. However, there is a trade-off between the need to synchronize and the need to stick to the individually different ideal time for the switch. We model this situation, assuming two mechanisms for achieving synchronization: either to be ready before the ideal individual moment, or to wait beyond it. The model identifies an optimal combination of readiness and waiting that brings the maximum benefit, in dependence on parameters including relative costs of nonsynchrony, acting too early, and acting too late. The model is examined in two variants, without or with communication between the animals about their preparedness to synchronize. For a majority of parameter values, the optimal strategy is to synchronize without communication (by just reacting to the other animal's action) and be ready before the ideal time, but not to wait. This strategy leads to premature switches in pairs compared to single animals. Communication only pays off when communicating is cheap and acting late is cheaper than acting prematurely. In this situation, communication is coupled with a pure waiting strategy and results in delayed switches. The model shows that synchronization is not symmetric in time which is a consequence of the inherent informational asymmetry of time. Author Affiliation: (a) Faculty of Science, University of South Bohemia, Aeske BudAjovice (a ) Ethology Group, Institute of Animal Science, Prague, Czech Republic Article History: Received 13 October 2006; Revised 14 February 2007; Accepted 3 April 2007 Article Note: (miscellaneous) MS. number: 9141