Understanding potential implications for non-trophic parasite transmission based on vertebrate behavior at mesocarnivore carcass sites

Abstract

High infection risk is often associated with aggregations of animals around attractive resources. Here, we explore the behavior of potential hosts of non-trophically transmitted parasites at mesocarnivore carcass sites. We used videos recorded by camera traps at 56 red fox (Vulpes vulpes) carcasses and 10 carcasses of other wild carnivore species in three areas of southeastern Spain. Scavenging species, especially wild canids, mustelids and viverrids, showed more frequent rubbing behavior at carcass sites than non-scavenging and domestic species, suggesting that they could be exposed to a higher potential infection risk. The red fox was the species that most frequently contacted carcasses and marked and rubbed carcass sites. Foxes contacted heterospecific carcasses more frequently and earlier than conspecific ones and, when close contact occurred, it was more likely to be observed at heterospecific carcasses. This suggests that foxes avoid contact with the type of carcass and time period that have the greatest risk as a source of parasites. Overall, non-trophic behaviors of higher infection risk were mainly associated with visitor-carcass contact and visitor contact with feces and urine, rather than direct contact between visitors. Moreover, contact events between scavengers and carnivore carcasses were far more frequent than consumption events, which suggests that scavenger behavior is more constrained by the risk of acquiring meat-borne parasites than non-trophically transmitted parasites. This study contributes to filling key gaps in understanding the role of carrion in the landscape of disgust, which may be especially relevant in the current global context of emerging and re-emerging pathogens. Graphical abstract

Wolf Is Back: A Novel Sensitive Sentinel Rejoins the Trichinella Cycle in the Western Alps

“…The last scenery is unlikely in the Alps since wolf is a protected species in the European Union and Switzerland; for this reason, wolf carcasses are made available to veterinary diagnostic centers or other scientific institutions, even when culling is allowed for mitigation of livestock depredation [ 66 ]; (iv) possible reluctance of other Trichinella maintenance hosts, in particular foxes, to feed on wolf carcasses, a neglected though epidemiologically intriguing issue. Previous experimental work on models other than wolf carcasses has shown that foxes make to avoid or delay the consumption of mesocarnivore carcasses [ 67 , 68 ], including conspecifics; (v) the so far limited mortality due to intra-specific aggressiveness, a density-dependent behavior which, in turn, could favor cannibalism. Expectedly, intra-specific aggressiveness will rise in the next future in parallel with the increasing alpine wolf population size, as occurred in North America under similar demographic conditions [ 69 ]; (vi) the influence of climate change, whose signal is stronger in mountain systems worldwide [ 70 ], implying a faster degradation of carcasses by necrophilic invertebrates [ 71 ] and, in winter, a shorter life expectancy of Trichinella larvae due to scarce snow precipitation and the consequent vanishing of the subnivium protective effect [ 72 ].…”

Divergent water requirements partition exposure risk to parasites in wild equids

“…Zebra dung density was not shown to change with distance from water, but this was based on 150-m long transects; our study builds on this to show that, when measured at a greater spatial scale, zebra dung density declines with distance from water up to about a kilometer away. Similar dynamics may be produced by other attraction points on the landscape, many of which may also draw in multiple species, such as carcasses (Gonzálvez et al, 2021), flower patches visited by various pollinators (Graystock et al, 2015), or stopover sites for migratory birds (Emmenegger et al, 2018). However, using this principle to understand transmission dynamics in a multi-host, multi-parasite system requires considerable knowledge of the study system and host-parasite dynamics for each member of the transmission network (Streicker et al, 2013).…”

Top‐predator carrion is scary: Fight‐and‐flight responses of wild boars to wolf carcasses

“…During ca. 40 days (period after which the carcasses were mostly composed of skin, bones, and other hard tissues), we recorded the behavior of animals approaching these carcasses using 10‐ to 60‐s videos (taken after detection of movement; interval between consecutive videos: 1 min; for more details, see Gonzálvez, Martínez‐Carrasco, & Moleón, 2021 ; Gonzálvez, Martínez‐Carrasco, Sánchez‐Zapata, et al, 2021 ). Images recorded by the cameras were grouped into “events”, that is, groups of consecutive videos of individuals of the same species taken more than 30 min apart (Gonzálvez, Martínez‐Carrasco, Sánchez‐Zapata, et al, 2021 ).…”

“…On the other hand, a fresh carcass, especially that of a predator, can also be scary in itself, as the animals approaching it may not be sure if the animal is dead or just sick, injured, or asleep, in which case it could turn on them. However, the scientific community has just started to uncover how animals respond to carnivore carcasses (e.g., Gonzálvez, Martínez‐Carrasco, & Moleón, 2021 ; Gonzálvez, Martínez‐Carrasco, Sánchez‐Zapata, et al, 2021 ), probably due in part to the difficulties in obtaining this type of carcass. In particular, the extent to which dead carnivores may frighten remains virtually unexplored to date.…”