15Diurnal species can reduce the cost of the trade-off between feeding and predation risk by 1) 16 performing low-quality (vigilance while performing another behavior) instead of high-quality 17 vigilance (only performing vigilance) or 2) by vigilance coordination either by taking turns 18 acting as sentinels or by synchronizing vigilance bouts. A sentinel system assumes that sentinels 19 are located at raised positions, alarm signal, and alternate vigilance bouts. However, many 20 species with a described sentinel system have not been tested yet for coordination. We set out to 21 study coordinated behavior and the reasons for this behavior in the invasive Barbary ground 22