School of Natural Sciences, University of Tasmania, Sandy Bay, Tasmania 7001, Australia.
ARC Centre of Excellence for Australian Biodiversity and Heritage, Sandy Bay, Tasmania 7001, Australia.
Proc Biol Sci. 2022 Oct 26;289(1985):20220521. doi: 10.1098/rspb.2022.0521.
Scavenging by large carnivores is integral for ecosystem functioning by limiting the build-up of carrion and facilitating widespread energy flows. However, top carnivores have declined across the world, triggering trophic shifts within ecosystems. Here, we compare findings from previous work on predator decline against areas with recent native mammalian carnivore loss. Specifically, we investigate top-down control on utilization of experimentally placed carcasses by two mesoscavengers-the invasive feral cat and native forest raven. Ravens profited most from carnivore loss, scavenging for five times longer in the absence of native mammalian carnivores. Cats scavenged on half of all carcasses in the region without dominant native carnivores. This was eight times more than in areas where other carnivores were at high densities. All carcasses persisted longer than the three-week monitoring period in the absence of native mammalian carnivores, while in areas with high carnivore abundance, all carcasses were fully consumed. Our results reveal that top-carnivore loss amplifies impacts associated with carnivore decline-increased carcass persistence and carrion access for smaller scavengers. This suggests that even at low densities, native mammalian carnivores can fulfil their ecological functions, demonstrating the significance of global carnivore conservation and supporting management approaches, such as trophic rewilding.
大型食肉动物的清除作用对于生态系统的功能至关重要，它可以限制腐肉的积累，并促进广泛的能量流动。然而，世界各地的顶级食肉动物已经减少，引发了生态系统内的营养转移。在这里，我们将以前关于捕食者减少的研究结果与最近有本地哺乳动物食肉动物损失的地区进行了比较。具体来说，我们研究了两种中型清道夫（入侵的野化猫和本地森林乌鸦）对实验放置的尸体的自上而下的控制。在没有本地哺乳动物食肉动物的情况下，乌鸦受益最大，它们的觅食时间延长了五倍。猫在没有本地主要食肉动物的地区会猎食一半的所有尸体。这比其他食肉动物密度较高的地区多了八倍。在没有本地哺乳动物食肉动物的情况下，所有尸体的存活时间都超过了三周的监测期，而在食肉动物丰富的地区，所有尸体都被完全消耗。我们的研究结果表明，顶级食肉动物的减少加剧了与食肉动物减少相关的影响，即增加了腐肉的持久性和小型清道夫对腐肉的获取。这表明，即使在低密度的情况下，本地哺乳动物食肉动物也可以发挥其生态功能，这证明了全球食肉动物保护的重要性，并支持了一些管理方法，如营养恢复。
