The ecology and economics of shorebird conservation in a tropical human-modified landscape

摘要

Rapid and extensive land-use change in intertidal foraging habitat and coastal roosting habitat is thought to be driving major population declines of shorebirds migrating through the East Asian-Australasian Flyway. Along the Inner Gulf of Thailand, a critical stopover and wintering ground for these birds, artificial wetlands (salt pans and aquaculture ponds) have replaced much of the natural coastal ecosystem. We conducted a two-part study to (i) assess the importance of salt pans and semi-traditional aquaculture ponds to shorebirds and (ii) understand the economic forces that drive land-use change in this region by interviewing salt pan and aquaculture operators. Salt pans provide important roost habitat, particularly for shorter-legged birds, which are less able to utilize aquaculture ponds due to their greater depth. Moreover, three focal shorebird species foraged extensively in salt pans and semi-traditional aquaculture ponds, even when intertidal mudflats were exposed, suggesting that artificial wetlands could buffer against the impacts of degraded intertidal foraging areas for some shorebird species. Economic profits from salt production and semi-traditional aquaculture are similar. Risks to investment and per capita profitability are key factors in determining whether to convert land from one use (e.g. salt pan) to the other (aquaculture).Synthesis and applications. Salt pans provide an important resource to migrating shorebirds. As development pressures increase, operators may need financial incentives if salt pans are to be maintained over large areas. Although semi-traditional aquaculture is used less by shorebirds, drained ponds provide opportunities to roost and forage. Semi-traditional aquaculture operators should drain their ponds regularly to provide supplementary habitat for shorebirds. Use of nets and pond liners should be discouraged in both systems. Optimizing aquaculture pond and salt pan management for shorebirds could provide a more pragmatic, cost-effective and geographically extensive solution to conserving these birds than protected areas alone.