Testing for pre-breeding consistency in top marine predators: Implications for delayed maturity and buffering of environmental change

由于许多动物直到几岁才繁殖，它们的种群由大量繁殖前的个体组成。就海洋生物而言，由于这些前期繁殖者的大部分早期生活都是在海洋中度过的，我们几乎对它们的生物学一无所知。一个相关的问题是：为什么我们需要了解它们的生物学？首先，在某些物种中，预繁殖者可能占总种群的一半以上。其次，这一年龄段取代了因自然或人为危害而死亡的繁殖个体，因此成为环境变化的重要缓冲。预繁殖者可能会因为食物的原因而等待数年才能繁衍后代。食物在海洋环境中的分布是零星的，因此海鸟(以及海洋哺乳动物)进化出高度专业化的觅食行为来定位它们的猎物。这些行为只有在繁殖的鸟类中才能表现出来，这些技术可能需要很多年的时间才能学会，这就解释了为什么预繁殖者需要几年的时间才能成熟，但我们到目前为止还无法调查这一点。使用最近开发的法医技术(稳定同位素)，我们现在可以第一次研究繁殖前海鸟的个体觅食行为。利用这些信息，我们将能够确定觅食一致性的发展是否解释了为什么海鸟在第一次繁殖时表现出如此延迟的年龄。这一点也很重要，因为高保真度或个体觅食专业化可能意味着更容易受到气候变化、渔业或污染的威胁。如果预繁殖者没有表现出这些一致性，他们可能不太容易受到这些威胁的影响，因此可能是更重要的变化缓冲区。

Because many animals do not breed until they are several years old, their populations consist of a large number of pre-breeding individuals. In the case of marine organisms, because these pre-breeders spend most of their early life at sea, we know virtually nothing about their biology. A pertinent question is; why do we need to know about their biology? Firstly, pre-breeders can represent more than half of the total population in some species. Secondly, this age-class replace breeding individuals that die as a result of natural or artificial hazards, and therefore act as important buffers of environmental change. Pre-breeders may wait several years to breed because of food. Food is patchily distributed in the marine environment, and as a result seabirds (as well as marine mammals) have evolved highly specialised foraging behaviours to locate their prey. These behaviours have only been shown by breeding birds and it is possible that these techniques take many years to learn, thus explaining why pre-breeders take several years to mature, but we have not been able to investigate this thus far. Using recently developed forensic techniques (stable isotopes) we can now study individual foraging behaviours of pre-breeding seabirds for the first time. Using this information will enable us to determine whether the development of foraging consistencies explains why seabirds show such a delay in their age at first breeding. It is also important because high site fidelity or individual foraging specialisation may mean a greater vulnerability to the threat from climate change, fisheries or pollution. If pre-breeders do not exhibit these consistencies, they may be less susceptible to these threats and may therefore be even more important buffers of change.