Banking on extinction: endangered species and speculation
研究投机者囤积虎骨、象牙等野生动物商品，通过控制供给或压低价格来驱逐偷猎者，并发现低贴现率或高增长率反而可能加速物种灭绝。
Many wildlife commodities, such as tiger bones, bear bladders, ivory, and rhino horn, have been stockpiled in large quantities by speculators who expect that future price increases justify forgoing the interest income associated with current sales. When supply from private stores competes with supply from ‘wild populations’ (in nature) and when speculators are able to collude, it may be optimal to coordinate on an extinction strategy. We analyse the behaviour of a speculator who has access to a large initial store, and finds that it is optimal to deter poachers’ entry either by depressing prices (carefully timing own supply) or by depressing wild stocks. Which strategy maximizes profits critically depends on the initial wildlife stock and initial speculative stores. We apply the model to the case of black rhino conservation, and conclude it is likely that ‘banking on extinction’ is profitable if current speculators are able to collude. Contrary to conventional wisdom, we also find that extinction is favoured by such factors as low discount rates or high growth rates.