Figure 2. Conditions under which searching-in-gangs is likely to be observed when there are no non-roost members defending carcasses: (a) λ = 0.01, γ = 0.011, (b) λ = 0.01, γ = 0.09, (c) λ = 0.1, γ = 0.11, (d) λ = 0.1, γ = 0.9.

The darker shading denotes where FD is a strong ESS, while the unshaded regions are where SR is likely to invade and spread to fixation (resist reinvasion). The thin and thick lines represent values of i _crit for which a ₂₄ = a ₄₄ and a ₃₄ = a ₄₄ (n = i _crit) respectively (Table 1 in Tables S1). Above the thick line dominants are relatively effective at excluding subordinates and there is therefore a ‘dominance advantage’ (n<i _crit), while below there is no such advantage (n>i _crit).