Endowment inequality in public goods games: A re-examination

We present a clean test of whether inequality in endowments affects contributions to a public good. It is a clean test because, to our knowledge, it is the first to control for possible endowment effects. We find that the key adverse effect of inequality arises because the rich reduce their contributions when there is inequality

‘Doggedness’ or ‘disengagement’?:An experiment on the effect of inequality in endowment on behaviour in team competitions

Teams often suffer from a free rider problem with respect to individual contributions. That putting teams into competition with each other can mitigate this problem is an important recent insight. However, we know little about how inequality in endowment between teams might influence this beneficial effect from competition. We address this question with an experiment where teams contribute to a public good that then determines their chances of winning a Tullock contest with another team. The boost to efforts from competition disappears when inequality is high. This is mainly because the ‘rich’ ‘disengage’: they make no more contribution to a public good than they would when there is no competition. There is evidence that the ‘poor’ respond to moderate inequality ‘doggedly’, by expending more effort compared to competition with equality, but this ‘doggedness’ disappears too when inequality is high

Calling where it counts:Subordinate pied babblers target the audience of their vocal advertisements

For territorial group-living species, opportunities to reproduce on the natal territory can be limited by a number of factors including the availability of resources within a territory, access to unrelated individuals, and monopolies on reproduction by dominant group members. Individuals looking to reproduce are therefore faced with the options of either waiting for a breeding opportunity to arise in the natal territory, or searching for reproductive opportunities in non-natal groups. In the cooperatively breeding Southern pied babbler, Turdoides bicolor, most individuals who achieve reproductive success do so through taking up dominant breeding positions within non-natal groups. For subordinate pied babblers therefore, searching for breeding opportunities in non-natal groups is of primary importance as this represents the major route to reproductive success. However, prospecting (where individuals leave the group to search for reproductive opportunities within other groups) is costly and individuals rapidly lose weight when not part of a group. Here we demonstrate that subordinate pied babblers adopt an alternative strategy for mate attraction by vocal advertisement from within their natal territories. We show that subordinates focus their calling efforts on the edges of their territory, and specifically near boundaries with neighbouring groups that have potential breeding partners (unrelated individuals of the opposite sex). In contrast to prospecting, calling individuals showed no body mass loss associated with this behaviour, suggesting that calling from within the group may provide a 'cheap' advertisement strategy. Additionally, we show that subordinates use information regarding the composition of neighbouring groups to target the greatest number of potential mating partners