Consequences of habitat loss at migratory stopover sites: a theoretical investigation
Consequences of habitat loss at migratory stopover sites: a theoretical investigation
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DOI：
10.2307/3677014
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发表时间：
1999-12-01
影响因子：
1.7
通讯作者：
Ens, BJ
中科院分区：
文献类型：
--
作者：
Weber, TP;Houston, AI;Ens, BJ
我们使用一个动态优化模型来评估迁徙中途停留地栖息地丧失的后果。我们强调鸟类在中途停留期间的费用（例如获得能量的费用），场地使用的时间和鸟类可能用于执行迁移策略的行为规则。行为规则可能足够灵活，使鸟类在变化的环境中仍能产生最佳行为，或者这些规则可能导致次优行为。如果鸟类在变化的环境中表现最佳，越冬地的栖息地损失的影响最大，因为这个地点，不像中间停留地点，如果质量下降到阈值以下，就不能跳过。如果鸟类继续使用旧的行为规则，导致现在的次优行为，我们可以区分两种情况。鸟类可以继续使用恒定的觅食行为，这在许多情况下在未改变的环境中是最佳的。栖息地丧失的影响与栖息地丧失前的停留时间和离开一个地点的燃料负荷成正比。然而，栖息地丧失的影响并不取决于该网站内的位置。在某些情况下，预计鸟类会以低于最大值的强度觅食。如果鸟类的觅食行为适合于给定的燃料负荷、时间和地点，但不适合于改变的燃料增益，那么靠近繁殖地的地点的变化比更远的地点产生更大的影响。最后，我们讨论了栖息地丧失前未使用的网站的重要性。如果鸟类的行为最佳，这些网站可以在一个改变的环境中使用，并可以缓冲在其他网站的栖息地丧失。
We use a dynamic optimization model to assess the consequences of habitat loss at migratory stopover sites. We emphasize costs birds Fare during stopover (e.g. costs of gaining energy), the timing of site use and the behavioural rules birds might use to implement migratory strategies. Behavioural rules may be flexible enough that birds can still produce optimal behaviour in the changed environment, or the rules may result in suboptimal behaviour.If birds behave optimally in the altered environment, habitat loss on the wintering ground has the highest impact, because this site, unlike the intermediate stopover sites, cannot be skipped if the quality drops below a threshold. If birds continue to use the old behavioural rules that now result in suboptimal behaviour, we can distinguish two cases. Birds can continue to use a constant foraging behaviour that was optimal In the unaltered environment under many circumstances. Then the effects of habitat loss are proportional to the length of stay before habitat loss and the departure fuel load from a site. However, the effects of habitat loss do not depend on the location of the site within the. network.In some circumstances birds are expected to forage with intensities that are below maximum. If birds use the foraging behaviour that is appropriate for a given fuel load, time and site but inappropriate for the altered fuel gain,then changes at sites close to the breeding ground have a greater impact than more distant sites. Finally we discuss the importance of sites that are not used before habitat loss. If birds behave optimally these sites may be used in an altered environment and can buffer against habitat loss at other sites.