Avoidance of carnivore carcasses by vertebrate scavengers enables colonization by a diverse community of carrion insects

Abstract

Carrion resources sustain a complex and diverse community of both vertebrate and invertebrate scavengers, either obligate or facultative. However, although carrion ecology has received increasing scientific attention in recent years, our understanding of carrion partitioning in natural conditions is severely limited as most studies are restricted either to the vertebrate or the insect scavenger communities. Moreover, carnivore carcasses have been traditionally neglected as study model. Here, we provide the first data on the partitioning between vertebrate and invertebrate scavengers of medium-sized carnivore carcasses, red fox ( Vulpes vulpes (Linnaeus)), in two mountainous Mediterranean areas of south-eastern Spain. Carcasses were visited by several mammalian and avian scavengers, but only one carcass was partially consumed by golden eagle Aquila chrysaetos (Linnaeus). These results provide additional support to the carnivore carrion-avoidance hypothesis, which suggests that mammalian carnivores avoid the consumption of carnivore carcasses to prevent disease transmission risk. In turn, the absence of vertebrate scavengers at carnivore carcasses enabled a diverse and well-structured successional community of insects to colonise the carcasses. The observed richness and abundance of the most frequent families was more influenced by the decomposition time than by the study area. Overall, our study encourages further research on carrion resource partitioning in natural conditions.

Carcasses at Fixed Locations Host a Higher Diversity of Necrophilous Beetles

“…However, the bait site situation in the BFNP with regular and year-round carrion supply guarantees a localized increased carrion volume over time despite the vertebrate scavenger visitors. Consequently, besides the above-discussed facilitation hypotheses, a highly diverse successional insect community could be a result of the total carrion volume, commensurate with the results of Moleón [ 65 ] and Muñoz-Lozano [ 66 ].…”

“…Regarding carrion volume, Moleón [ 65 ] suggested that increased carrion biomass resulting from vertebrate scavenger reductions at carnivore carcasses enables a successional insect community of the remains. This was confirmed by a carnivore carcass avoidance-study of Muñoz-Lozano [ 66 ], showing a well-structured and diverse insect community consisting of necrophages, omnivores, and necrophilous predators and parasitoids. In contrast to the studies of Moleón [ 65 ] and Muñoz-Lozano [ 66 ], no carnivore carcasses were exposed at our fixed locations, and access by vertebrate scavengers, such as red foxes, pine martens, or Eurasian lynx, to the exposed roe and red deer carcasses took place [ 21 ].…”

“…This was confirmed by a carnivore carcass avoidance-study of Muñoz-Lozano [ 66 ], showing a well-structured and diverse insect community consisting of necrophages, omnivores, and necrophilous predators and parasitoids. In contrast to the studies of Moleón [ 65 ] and Muñoz-Lozano [ 66 ], no carnivore carcasses were exposed at our fixed locations, and access by vertebrate scavengers, such as red foxes, pine martens, or Eurasian lynx, to the exposed roe and red deer carcasses took place [ 21 ]. However, the bait site situation in the BFNP with regular and year-round carrion supply guarantees a localized increased carrion volume over time despite the vertebrate scavenger visitors.…”

Blow fly stable isotopes reveal larval diet: A case study in community level anthropogenic effects

“…In fact, some studies suggest that vertebrate scavengers actively avoid consuming carnivore carcasses, or at least conspecifics, as scavenging these resources may be associated with a greater likelihood of exposure to infectious diseases [ 35 ]. This avoidance strategy by vertebrate scavengers has also been shown to facilitate greater opportunities for invertebrate scavengers to exploit carnivore carcasses [ 36 ], which likely explains the carnivore bias in our blow flies collected in the national parks.…”

A biological invasion impacts ecosystem services: cane toads change the rate of scavenging and the suite of scavengers

“…2) might have consequences for the toads themselves. Necrophagous invertebrates are an important driver of carrion decomposition, and increase in abundance if carcasses are left unscavenged by vertebrates (Munoz‐Lozano et al 2019). More broadly, cane toads key in on resource patches that offer abundant prey (González‐Bernal et al 2013, Feit et al 2015).…”